Initial evaluation of briquetting possibilities of CaO-containing paper production waste

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IN

DEGREE PROJECT MATERIALS SCIENCE AND ENGINEERING, SECOND CYCLE, 30 CREDITS

,

STOCKHOLM SWEDEN 2018

Initial evaluation of briquetting

possibilities of CaO-containing

paper production waste

For use in metallurgical processes

XIA WEI

KTH ROYAL INSTITUTE OF TECHNOLOGY

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Abstract

Paper and pulp industry and steel industry are two major industries in Sweden, both of which are facing big challenges to treat their waste products properly. In this thesis work, initial evaluation of mechanical properties of briquettes made of waste products was performed. Three different CaO-containing waste products (Mesa, Kalk, Fly Ash) from Stora Enso and SCA were pressed with one kind of binding material (AOD slag) from Outokumpu. Drop tests were carried out to test the impact strength of the lab-made briquettes.

Three different parameters were investigated of their influence on the impact strength of the briquettes: 1) Composition of briquettes 2) Heat treatment procedure 3) Exposure time to open air. A total of 97 briquettes were pressed. Drop test results show that for different material based briquettes, heat-treatment and exposure to open air had different influence on the final impact strength. In order to get best impact strength, MB briquettes (90% Mesa +10% AOD slag) heat treated at 850℃, KB briquettes (90% Kalk +10% AOD slag) heat treated at 850℃ and FC briquettes (80% Fly Ash + 20% AOD slag) exposed to open air for 20 days are recommended.

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1 Introduction

Paper industry and steel industry are two important industrial sectors in Sweden. According to statistics, 4.4 million tons of crude steel was produced in 2015 [1], the output value of steel and metal industry occupies 8.7% of total industry output in 2015 in Sweden [2]. Paper industry shared about 7.8% of total industry output in Sweden [2]. For paper industry, a large amount of waste product is produced every year. Figure 1 shows the statistics of waste products of paper industry from 2004 to 2014 in Sweden. A total of 1.46 million tons of waste product was produced from paper industry in 2014 [3].

Normally, waste management of pulp and paper industry includes energy recovery, fertilizer and ethanol production, around 17% of waste generated from European pulp and paper mills goes to landfill [4]. Thus, it is important to treat those waste products properly to meet the goal of Roadmap 2050 to create a low carbon future [5].

A typical ore-based steelmaking process is shown in Figure 2. Flux, also known as slag former, is a very important additive in the refining processes of steelmaking. A typical slag former contains mostly metal oxides, such as CaO, Al2O3, SiO2, MgO, and some amount of C. For

example, the desulfurization process in ladle furnace, the reaction is shown in Eq.(1), which takes most of dissolved sulphur out of liquid steel.

CaO + S → CaS + O (1)

Slag formers are normally a mixture of different components. There are several sources of slag formers. One comes from the slag of the company’s own steel making process. The advantages

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 2004 2006 2008 2010 2012 2014 M il lio n to n Year

waste production of paper industry

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of this source are that these slags have known composition and are environmental-friendly due to reuse of materials. Others might be mineral ores like limestone or dolomite.

1.1 Social and Ethical Considerations

This thesis work investigated the possibility of utilizing waste products from paper industry as slag former into metallurgical processes by impact strength test and melting experiment. Mesa, Kalk and Fly Ash are three main waste products investigated in this work. They all consist of similar components compared with slag former used in real steelmaking processes. Therefore, the replacing of slag former using waste products from paper mills is a win-win trade for both steel industry and paper industry. Steel industry can possibly lower their cost and carbon footprint, and paper industry can earn more profit from selling waste and reduce landfill. [6]

1.2 Pre-Study and Conclusion

A pre-study of investigating the possibility of using the waste products from paper industry as a replacement of flux (slag former) in steel industry has been carried out by the author of this thesis within course MH2450, International Seminar in Material Processes at KTH [7]. Five different waste products from paper industry were investigated: Mixed Bio-sludge (BS), Fiber Reject (FR), Fly Ash, Kalk and Mesa. They are divided into two groups, carbon-based group and CaO-based group. Mixed Bio-sludge and Fiber Reject belongs to the carbon-based group due to 30-40% of carbon content. CaO-based waste products are Fly Ash, Kalk and Mesa containing 50-85% CaO compounds. Comparison results between the composition of waste products and real slag for different furnaces indicates whether the replacement is possible or not. Four furnaces were investigated: blast furnace, electric arc furnace, argon oxygen decarburization converter (AOD converter) and cupola furnace. 3-5 typical compositions of

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slags used for each furnace was found in the literature, which formed a reference range for different furnaces. By comparing the composition of waste products from paper industry with the reference range, following conclusion can be drawn:

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2 Literature Review of Waste Treatment

Pulp and paper industry is the world’s sixth largest polluter after oil, cement, leather, textile and steel industries [8]. In the production process of paper and pulp in North America, about 40-50 kg of dry sludge is generated when producing every 1 ton paper products. About 70% of which is primary sludge while the rest is called secondary sludge or bio-sludge [9].

Primary sludge is produced in clarification of process water by treatment like dissolved air flotation. The sludge consists of mostly wood fibre like cellulose, hemicellulose and lignin. Primary sludge is easy to dewater by mechanical methods. Secondary sludge or bio-sludge is generated in the clarifier within wastewater treatment of paper mill, and it is difficult to handle, usually it is either recycled (e.g. to board industry) or incinerated or disposed to landfill [8] [9]. In pulp and paper industry, about 19% of generated sludge is incinerated for energy recovery. Other applications include producing soil fertilizer and ethanol. However, the most common waste management has always been the landfill disposal [4].

Landfilling is discouraged across the world since it causes long lasting environmental issues related with leaching and greenhouse gas production [10]. In European region, strict regulations were setup to reduce or prevent landfilling. Only limited wastes which satisfy the requirements of the European Landfill Directive (1999/31/EC) can be disposed to landfill [11]. The Confederation of European Paper Industries (CEPI) supports a complete ban of landfilling and incineration in the European Union in agreement with the Waste Framework Directive (2008/98/EC) [12]. This directive emphasises the importance of recycling over energy recovery and disposal. Also, the European Commission Roadmap to a Resource Efficient Europe (COM (2011) 571) [13] setup goals to be achieved by the year of 2020 in which waste will be utilized as a resource and energy recovery will only be performed to materials that are un-recyclable [4].

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waste products from pulp and paper industry. The reason of replacing is that both wastes from paper industry and flux of steel industry share similar components, mostly consist of metal oxides and carbon.

In steel industry, slag former is usually compound of different minerals or other oxides containing materials. Most common combinations are: limestone, dolomite, crude aluminum and slags produced from steelmaking process [20] [21].

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3 Experimental Procedure

In traditional steel industry, waste products are utilized in briquette form, photograph and schematic illustration of typical industry briquette are shown in Figure 3(CaO and dolomite are small lumps). Most of the waste products received from paper industry are in powder forms after drying. Thus, briquetting process is needed to press the powders into briquettes. The reason of using briquette-form slag former instead of powder-form slag former is that briquettes are easier to handle for transportation and charging. The briquette should have good mechanical properties and good reactivity with liquid steel, which means it can dissolve fast when charged into the furnace.

Parameters, which influence the impact strength of briquettes, were investigated: 1) briquette composition 2) heat treatment procedure 3) exposure time to open atmosphere. Drop test was chosen to be the method to test the impact strength of briquettes.

Hydraulic pressing was performed to press the powders into the form of laboratory briquettes. Then, some briquettes were taken to further treatment (heat treatment or exposure to open atmosphere) to investigate if the treatment can enhance the impact strength of the briquettes and how much the impact strength can improve. Briquettes with and without treatment were carried out with drop test to test the impact strength of the briquettes. And later, melting experiments were carried out to investigate the refining abilities of the briquettes when added into molten steel with industrial slag.

In a typical steelmaking process, slag formers are charged into furnace in the refining step such as AOD converter or ladle furnace. Most common reactions that happen in the refining process are decarburization and desulphurization which are shown in Eq.(2) and Eq.(3).

C +1

2𝑂2→ CO (2)

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2CaO + 2S → 2CaS + O2 (3)

In melting experiment of this thesis work, the briquettes made of waste products from pulp and paper industry were partially mixed with real slag former used in Outokumpu, different recipes will be evaluated to see how the S, P and O level in the final steel changes.

Ten different recipes were used to make briquettes based on different waste materials with one kind of binding material (AOD slag). For each recipe, at least 3 briquettes were made in order to reduce the systematic error.

3.1 Materials for Drop Test

Materials used in this thesis work are Fly Ash powder, Mesa powder, Kalk powder and powdered AOD slag. Pictures of these four materials are shown in Figure 4. Mesa, Kalk and Fly Ash are waste products from Stora Enso and SCA. Fly Ash comes from combustion process of internal and external fuels from Stora Enso. AOD slag has been found to have some binding properties. The main components of AOD slag are CaO, SiO2, Al2O3, MgO, and FeO. The main

composition of Mesa, Kalk and Fly Ash is listed in Table 1, while they might vary between bathes and sites.

Figure 4 Pictures of Fly Ash, Mesa, Kalk and AOD slag

In this project, briquettes with different recipes were tested. They were labelled with different names, which can be seen in chapter 3.7.

Table 1 Main composition of waste products from paper industry

Content CaO MgO SiO2 Al2O3 K2O Na2O P*

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3.2 Briquetting Process

A special hollow cylinder mould was used for hydraulic pressing of briquettes in this thesis work. Approximately 20g of powder (pure or mixed) was added into the hollow part of the mould with a supporting part underneath. Then another cylinder which exactly fit the hollow part was inserted into it. When the mould was assembled, it was put in a hydraulic pressing machine as shown inFigure 5. A pressure of 18 MPa was applied to press the powder into the form of a briquette. The pressure was kept for 10 seconds before it was released. After that the briquette was removed from the machine and weighted. The operation was carried out at room temperature.

3.3 Heat Treatment of Briquettes

Two heat treatment procedures were tested to investigate the influence of different heat treatments procedures.

The temperature profiles of heat treatments up to 500°C and 850°C are shown in Figure 6. The furnace was set to run with a constant heating rate (10°C/min). The two-step heating gives the gases enough time to get out of the briquettes, preventing significant cracks.

• The furnace was heated up from room temperature to 500°C for 50 minutes.

• The furnace was kept at 500°C for 30 minutes, to give enough time for decomposition of water containing components.

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• For 500°C heat treatment, the furnace was shut down and cooled with the furnace door closed and the briquettes kept inside the furnace until the furnace was cooled to room temperature.

• For 850°C heat treatment, the furnace was continuously heated up from 500°C to 850°C for 35 minutes.

• The furnace was kept at 850°C for 60 minutes, for decomposition of CaCO3.

• The furnace was shut down and cooled with the briquettes inside to room temperature.

3.4 Exposure to Open Atmosphere

In steel industry, the briquettes are exposed to air to enhance their mechanical properties, usually 7-35 days are applied. Three briquettes of certain recipes were exposed to open air for a designated time in order to compare the impact strength difference between exposed briquettes and heat-treated briquettes.

Figure 7 shows how briquettes were exposed to air in the lab. Some recipes were chosen to study how exposure to open air will influence the briquettes impact strength. Different exposure time was chosen, ranging from 7 to 35 days. 90% Mesa-based briquettes and 90% Kalk-based briquettes were chosen to study the long time (35 days) exposure influence. 90% Fly Ash-based briquettes and 100% Fly Ash-based briquettes were chosen to study how the different exposure time will influence the impact strength of briquettes. Three exposure length is chosen, 7 days, 20 days and 35 days. Detailed information can be seen in Table 4-7.

0 100 200 300 400 500 600 700 800 900 1000 0 50 100 150 200 250 300 Tem p era tur e ( oC) Time (min)

850℃ Heat Treatment 500℃ Heat Treatment

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3.5 Drop Test Procedure

• The briquette is dropped to a metal plate by gravity from a distance of 1.0 meter, with the flat face down. A schematic illustration is shown in Figure 8.

• If the briquette broke into several pieces, for example into 3 pieces with different size as shown in the figure, the biggest piece (a) is collected and weighted for the next drop. The other pieces (b and c) are collected as well for further analysis.

• The test is stopped when the weight of biggest piece is less than 1% of initial briquette mass or the drop number reaches 15 times.

Figure 7 Briquettes with exposure to open air

Figure 8 Schematic illustration of drop test

a b

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3.6 Melting Experiment

Figure 9 shows a schematic illustration of induction furnace used in this thesis work. Steel scrap were melted at 1580-1600℃ in an Al2O3 crucible in the induction furnace and held

15-30 min for homogenization of melt components and temperature.Then briquette slag former was added. Steel samples were taken using a quartz tube 5 min, 15 min and 30 min after addition of briquette slag former, and then the ingot was quenched in cold water and then cooled down in open air. Same procedures will be repeated with steel from electric arc furnace (EAF) to see if the impurities from briquettes will end up in the metal or slag.

Figure 9 Induction furnace used in this thesis work

3.6.1 Materials for Melting Experiment

The steel scrap used in this melting experiment is stainless steel 304 from Outokumpu. Around 200 g of scrap was used each time. The composition of 304 steel is listed in Table 2. The slag former used in this thesis work is a mixture of lab-made briquettes (Fly Ash-based) and real slag former. The total composition of mixture is listed in Table 3, which consists of 45% Kalk, 45% dolomite and 10% lab-made briquette (containing 90% Fly Ash). The added weight of slag former was set to 10% of the scrap added into the induction furnace (~20 g).

Table 2 Composition of stainless steel 304 used in this thesis work [wt %]

C Mn P S Si Cr Ni N

0.08 2 0.05 0.03 0.8 18.0-20.0 8.0-10.5 0.1

Graphite Crucible

Al

₂

O

₃

Crucible

Fire-Proof Brick

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Table 3 Mixed slag former composition [wt %]

CaO MgO SiO2 Al2O3 FeO S K2O Na2O 74.2 17.9 3.9 1.6 0.4 0.0007 0.05 0.06

The main focus of melting experiment is to see how the impurity contents will change in metal and slag. Theoretical sulphur distribution (Ls) was calculated and will be compared with later experiment results. Eq. (4) [24] is the equation used to calculate Ls in this thesis work.

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The expected sulphide capacity is 5.65 according to calculation. The detailed calculation process of sulphide capacity is listed in Appendix D.

log 𝐿

_𝑆

= 𝑙𝑜𝑔

(%𝑆)𝑠𝑙𝑎𝑔

[%𝑆]𝑚𝑒𝑡𝑎𝑙

= −

935

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3.7 General Information of Drop Test

Table 4 General drop test information of Mesa-based briquettes

Notes:*: negative number means weight loss, while positive number means weight gain. Briquettes Composition (wt%) _Initial Weight (g) Weight after Heat Treatment (g) Heat Treatment Temperature (℃) Exposure Time (d) Weight after Exposure (g) Number of Drops Final Weight (g)

Weight change due to Heat Treatment/

Exposure *

Weight loss due to drop

test * Mesa AOD slag

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Table 5 General drop test information of Kalk-based briquettes

Notes:*: negative number means weight loss, while positive number means weight gain. Briquettes Composition (wt%) Initial Weight (g) Weight after Heat Treatment (g) Heat Treatment Temperature (℃) Exposure Time (d) Weight after Exposure (g) Number of Drops Final Weight (g)

Exposure *

test * Kalk AOD slag

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Table 6 General drop test information of Fly Ash-based briquettes

Exposure *

test * Fly Ash AOD slag

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Table 7 General drop test information of Fly Ash-based briquettes

Exposure *

test * Fly Ash AOD slag

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4 Results and Discussion

4.1 Heat-Treated Briquettes vs. Non-Heat-Treated Briquettes

Heat treatment up to 850℃ is chosen to be an example in this section, the difference between 850℃ heat-treated briquettes and 500℃ heat-treated briquettes will be discussed in chapter 4.2. In all figures in this chapter, H means heat-treated briquettes while N means non-heat-treated briquettes. Error bars in the figures represent the standard deviations of experiment results.

4.1.1 Mesa-Based Briquettes

Figure 10 is the impact strength comparison between heat-treated and non-heat-treated Mesa-based briquettes. Lines with same colour means briquettes with same composition, solid line means heat treated at 850℃ while dotted line means non-heat-treated. MA means pure Mesa, MB means 90% Mesa mixed with 10% AOD slag and MC means 80% Mesa mixed with 20% AOD slag. It is clear that for Mesa-based briquettes, heat-treated briquettes show significantly better impact strength than treated briquettes according to Figure 10. For non-heat-treated Mesa-based briquettes, drop test stopped after 5-10 drops, because less than 1% of initial mass remained. However, for heat-treated briquettes, about 70%-80% of initial weight remained after 15 drops. When looking at results only for heat-treated briquettes, it is interesting to notice that MB briquettes which contains 90% Mesa and 10% AOD slag shows the best impact strength among all. After 2 drops, MB briquettes remained average 10-15% more initial weight compared with MA and MC briquettes. Non-heat-treated briquettes did not show that kind of trend, the briquettes all broke very fast, less than 10% of initial weight was left after 5 drops.

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4.1.2 Kalk-Based Briquettes

Figure 11is the comparison between drop test results of Kalk-based briquettes heat treated at 850℃ and briquettes without heat treatment. Lines with same colour means briquettes with same composition, solid line means heat treated at 850℃ while dotted line means non-heat-treated. For non-heat-treated briquettes, KA briquettes (pure Kalk), KB briquette (90% Kalk + 10% AOD slag) and KC briquette (80% Kalk + 10% AOD slag) broke very fast during drop test, less than 1% of initial weight remained after 3-6 drops. Heat treatment had different impact on the impact strength of Kalk-based briquettes. For KC briquettes, the improvement was not very significant, the weight loss was slower and smooth after 3drops, about 7% of initial weight was left after 15 drops. Heat-treated KA briquettes showed slightly better impact strength than heat-treated KC briquettes. 28% of initial weight remained after 6 drops, and the weight loss trend become smooth after that, about 13% of initial weight remained after 15 drops. Heat-treated KB briquettes showed best impact strength among all Kalk-based briquettes and had most significant impact strength improvement due to heat treatment, 82% of initial weight was remained after 4 drops, and 33% of initial weight was left after 15 drops.

0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops KAH KBH KCH KAN KBN KCN

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4.1.3 Fly Ash-Based Briquettes

Figure 12 is comparison between drop test results of Fly Ash-based briquettes with 850℃ heat treatment and briquettes without heat treatment. Lines with same colour means briquettes with same composition, solid line means heat treated at 850℃, while dotted line means non-heat-treated. For FA briquettes (pure Fly Ash briquettes), the weight loss trends without heat treatment and with heat treatment are similar according to the blue lines in the figure, which means that heat treatment has no significant influence on the impact strength of FA briquettes. For FB briquettes (90% Fly Ash + 10% AOD slag) and FC briquettes (80% Fly Ash + 20% AOD slag), the briquettes after heat treatment lost less weight compared with non-heat-treated briquettes. Non-heat-treated FB and FC briquettes had similar weight loss trend as FA briquettes. However, heat-treated briquettes showed better impact strength, more weight was remained. Heat-treated FC briquettes remained more initial weight (10~30%) at first 10 drops compared with FB briquettes. Similar trend was showed in the last 5 drops. It is clear that heat-treated FC briquettes had best impact strength among all briquettes, average of more than 90% of initial weight was left after 7 drops.

0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 Wei gh t Per ce n tage Number of Drops FAH FBH FCH FAN FBN FCN

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4.2 Briquettes Heat Treated at 850℃ vs Briquettes Heat Treated at 500℃

Figure 13 is the drop test results comparison between heat-treated briquettes of two different temperatures, 500 ℃ and 850 ℃ . Lines with same colour means briquettes with same composition, solid line means heat treated at 850℃ while dotted line means heat treated at 500℃. It is interesting to notice that for FB briquettes (90% Fly Ash + 10% AOD slag), the briquettes’ impact strengths were quite similar to the drop test results of briquettes heat treated at 500℃ and 850℃. FB briquettes heat treated at 850℃ remained slightly more weight before the 11th_{drop, then FB briquettes heat treated at 500℃ remained more weight after that.}

For MB briquettes (90% Mesa +10% AOD slag) and KB briquettes (90% Kalk + 10% AOD slag), heat-treated briquettes at 850℃ showed significant better impact strength than briquettes heat-treated at 500℃. For MB briquettes, heat-treated briquettes at 500℃ remained only 8% of initial weight while heat-treated briquettes at 850℃ remained 81% of initial weight after 15 drops. For KB briquettes heat-treated at 500℃, less than 1% of initial weight was left after 6 drops, the briquettes broke very fast according to the curve. However, KB briquettes heat-treated at 850℃ remained 34% of initial weight after 15 drops. Heat treatment at 850℃ did improve the impact strength of Mesa and Kalk-based briquettes but had little impact on Fly Ash-based briquettes. The reason of different impact strength might be the decomposition reaction of CaCO3 into CaO and CO2 happens at 850℃, which makes the remaining metal

oxides bind together firmly with the help of binder (AOD slag) and high temperature.

0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops MB-850 KB-850 FB-850 MB-500 KB-500 FB-500

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4.3 Briquettes with Different Exposure Time to Open Atmosphere

4.3.1 35-Day-Exposed Briquettes vs Unexposed Briquettes

4.3.1.1 MB Briquettes (90% Mesa + 10% AOD slag)

Figure 14 is the drop test results comparison for MB briquettes with and without exposure to open air. E means ‘exposued briquettes’, NE means ‘non-heat-treated and un-exposed briquettes’ and HT mean ‘heat-treated briquettes’, similar nomenclature is used for FB and F briquettes in following chapters. It is clear shown in the figure that long time (35 days) exposure did not have obvious influence on the impact strength of MB briquettes. Only small improvements on the impact strength were achieved in the first 3 drops according to the plots. For MB briquettes, the average remaining weight was less than 10% after 4 drops if heat treatment is lacking. However, heat-treated MB briquettes showed significant better impact strength than those without heat treatment. Average over 80% of initial weight was remained after 15 drops. That results indicate that long time exposure (35 days) to air has little improvements on the impact strength of non-heat-treated MB briquettes.

Figure 14 Average comparison between MB briquettes with and without 35 days exposure to open air 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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4.3.1.2 FA Briquettes (100% Fly Ash)

Figure 15 is the drop test results comparison for pure Fly Ash briquettes with different conditions of heat treatment and exposure. It is interesting to notice that drop test results for FA briquettes were different from MB briquettes. For non-heat-treated pure Fly Ash briquettes, similar weight loss trend was shown by the drop test results. As shown in Figure 15, the weight loss curve for FA-NE briquettes and FA-HT briquettes are two intertwined curves, which mean that heat treatment does not have significant improvement on the impact strength of pure Fly Ash briquettes. However, for pure Fly Ash briquettes with long time (35 days) exposure to open air, drop test results showed that average about 10-20% more weight was remained for each drop compared with other two circumstances. That means long time (35 days) exposure to open air is a better choice to strengthen the briquettes of pure Fly Ash.

4.3.1.3 FB Briquettes (90% Fly Ash + 10% AOD slag)

Figure 16 is the drop test results comparison for FB briquettes with and without long time exposure to open air. Unlike MB briquettes, non-heat-treated FB briquettes with 35 days exposure to open air showed similar weight loss trend as heat-treated FB briquettes. Both of them show better impact strength than non-heat-treated FB briquettes without exposure. Since heat-treated FB briquettes only remained slightly more weight (10% or less) in each drop, long time (35 days) exposure to open air is a good method for FB briquettes to gain good impact strength and save energy.

Figure 15 Average comparison between pure Fly Ash briquettes with and without 35 days exposure to open air

0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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4.3.1.4 KB Briquettes (90% Kalk + 10% AOD slag)

Table 8 Changes of MB and KB briquettes with exposure to open air

Table 8 is the morphology changes of MB and KB briquettes with exposure to open air. All briquettes have same diameter at the beginning since they were pressed in the same mould. It can be seen from the table that the volume of KB briquettes expanded a lot during exposure, compared with MB briquettes which kept its original shape all the time. After 19 days of exposure, the KB briquettes was almost ‘powders stood in briquettes form’. As shown in the

Figure 16 Average comparison between FB briquettes with and without 35 days exposure to open air

0 day 14 days 19 days 27 days

MB Briquettes KB Briquettes 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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table, it could be destroyed easily by only gentle touch. After 27 days of exposure, it can be seen that KB briquettes expanded a lot and got in touch with each other. The ‘briquettes’ were no longer briquettes but completely powders, and the volume were so big that the grains could not stick together anymore, so those ‘briquettes’ fell into powders. One possible reason for that transformation could be that those briquettes absorb water content in the air and expand volume. When the volume reaches some certain limit, the binding forces between the grains cannot stand against gravity, leading to collapse as shown in the table. That phenomenon indicates that Kalk-based briquettes cannot be stored unprotected in bare air.

4.3.2 Impact of Different Exposure Time to Open Atmosphere (7days vs 20days vs

35days)

4.3.2.1 FA Briquettes (100% Fly Ash)

Figure 17is the drop test results comparison for pure Fly Ash briquettes with different exposure time. The purple reference line is the weight loss trend for non-heat-treated pure Fly Ash briquettes without exposure to open air. It can be seen from the figure that three different exposure length all have positive influence on the impact strength of pure Fly Ash briquettes, but to different extent. In the first 3 drops, all exposed briquettes remained most of their initial weight (more than 99%), 20-day briquettes start to lose significant weight in the sixth drop. Briquettes with longest exposure time (35 days) was the worst briquettes compared with the other two. According to the figure, 20-day exposed briquettes have slightly better impact strength than 7-day briquettes, which indicates that for pure Fly Ash briquettes, exposure of 7 days is the best way to get ideal impact strength.

Figure 17 Comparison between pure Fly Ash Briquettes with different exposure time 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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4.3.2.2 FB Briquettes (90% Fly Ash + 10% AOD slag)

Figure 18is the drop test results comparison for FB briquettes with different exposure time to open air. The purple reference line is the weight loss trend for non-heat-treated FB briquettes without exposure to open air. It can be seen from the figure that, briquettes with 7 days exposure remained slightly more weight compared with reference line between 2nd_{to 5}th_drop,

and two lines starts to intertwine each other after that, which means that 7 days exposure to open air has small improvements on the impact strength of FB briquettes. However, FB briquettes with 20 days exposure and 35 days exposure have better impact strength according to the weight loss trend curve in the figure. For briquettes exposed to open air for 20 days, more than 99% of initial weight was remained in the first 5 drops, and then started to lose weight. About 17% of initial weight was remained in the end of the drop test (15 drops). FB briquettes with 20 days exposure to open air lost their weight more slowly in the beginning compared with FB briquettes exposed to open air for 35 days. But after 7 drops, the curve for 35 days and 20 days aligns. This set of comparison shows that for FB briquettes, 20 days exposure to open air could get ideal impact strength. Too long time of exposure might cause a decrease of impact strength due to water adsorption or other reasons.

4.4 Melting Experiment

The melting experiment was not successful for the reason that the crucible was melted by liquid steel. Three sampling were planned 5 min, 15 min, and 30 min after the steel was melted. The first 5-min sample was successfully taken out and quenched in cold water.

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However, when it was time for second sampling, solid surface stopped the sampling process. The furnace was observed under the protection of welding glasses. The Al2O3 crucible titled

when tried to take sample 2. Then the furnace was shut off. The Al2O3 crucible was cooled down

inside the furnace with cooling water system and air circulation on. After the Al2O3 crucible

cooled to room temperature, it was taken out. Figure 19 is the picture of the titled Al2O3

crucible. As can be seen the crucible was ‘welded’ with the fire-proof brick by the liquid steel and stayed in the same position when the second sampling process took place. It shows that from the top view that the bottom part of Al2O3 crucible was thinner than the upper part, which

indicates that reaction between liquid steel and Al2O3 dissolved the crucible and created a hole

in the bottom of Al2O3 crucible. This led to loss of liquid steel inside the Al2O3 crucible to the

surface of fire-proof brick and made holes in the brick surface.

Figure 19 Pictures of tilted Al2O3 crucible

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As listed in Table 3 inchapter 3.6, the mixture of slag former contains 74% of CaO, 4% SiO2 and 1.6% of Al2O3, which locates inside the red circle in Figure 20. That mean the slag former is still solid at 1600℃.

4.5 Overall Discussion

For non-heat-treated Mesa and Kalk-based briquettes, most of the weight was lost in the first few drops, normally less than 10% of initial weight remained after 5 drops. It means that for non-heat-treated Mesa and Kalk-based briquettes, poor impact strength was shown. Those briquettes are not strong enough for transportation and will break very fast during the charging process. However, for non-heat-treated Fly Ash-based briquettes, the weight loss trend is more moderate than the other two.

Improvements on impact strength due to heat treatment differs with composition. For Mesa-based briquettes, significant improvements can be observed, over 70% of initial weight was remained after 15 drops. However, about 6-33% of initial weight was remained for heat-treated Kalk-based briquettes. That means heat-treated Mesa-based briquettes have good impact strength for both transportation and charging process, while heat-treated Kalk-based briquettes have the possibilities to break into some large pieces during transportation and charging process but still much better than non-heat-treated briquettes. For Fly Ash-based briquettes, non-heat-treated FA (pure Fly Ash) briquettes showed similar weight loss trend compared with heat-treated FA briquettes, which means that heat treatment has barely influence on the impact strength of FA briquettes. FB (90% Fly Ash + 10% AOD slag) and FC (80% Fly Ash + 20% AOD slag) briquettes showed better impact strength after heat treatment. Briquettes containing different amount of binding material (AOD slag) and heat treated at same temperature have different impact strength. For Mesa-based briquettes, MA briquettes (pure Mesa) and MC (80% Mesa + 20% AOD slag) briquettes showed highly similar impact strength according to drop test results, MB briquettes (90% Mesa + 10% AOD slag) showed higher impact strength than the other two, approximately 10% more initial weight remained. For heat-treated Kalk-based briquettes, KB briquettes (90% Kalk + 10% AOD slag) showed best impact strength among all tested Kalk briquettes. KA briquettes (pure Kalk) was the second best while KC briquettes (80% Kalk + 10% AOD slag) showed worst impact strength among all testes Kalk briquettes.

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briquettes heat treated at 850℃, higher impact strength was shown due to decomposition of CaCO3.

Being exposed to open air had different influence on the impact strength of briquettes based on different materials. Kalk-based briquettes are not suitable to be exposed to open air due to volume expansion and collapse of briquettes. The improvement on the impact strength of FB briquettes (90% Fly Ash +10% AOD slag) were biggest compared with briquettes made by other recipes. For MB briquettes (90% Mesa +10% AOD slag), briquettes exposed for 35 days showed almost same weight loss trend as non-heat-treated briquettes, both briquettes lost their weight very fast, almost less than 10% of initial weight were left after 4 drops. However, heat-treated MB briquettes remained almost 80% of initial weight at the end of the drop test (15 drops). For FA (pure Fly Ash) briquettes, briquettes with 7 days of exposure to open air was the ideal way to get good impact strength. However, heat treatment had little improvement on the impact strength of the briquettes.

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5 Conclusion

For Mesa-based briquettes:

• Briquettes heat treated at 850℃ containing 90% Mesa and 10% AOD slag had the best impact strength among all tested Mesa-based briquettes.

• Heat treatment had big positive influence on the impact strength of Mesa-based briquettes. Briquettes containing 90% Mesa and 10% AOD slag had best impact strength after heat treatment, while pure Mesa briquettes and briquettes containing 80% Mesa and 20% AOD slag showed slightly less improvement on the impact strength. • 35 days exposure to open air had no improvements on the impact strength of

Mesa-based briquettes containing 90% Mesa and 10% AOD slag.

• Briquettes containing 90% Mesa and 10% AOD slag heat treated at 850℃ remained 57.94% more initial weight compared with those heat treated at 500℃.

For Kalk-based briquettes:

• Briquettes heat treated at 850℃ containing 90% Kalk and 10% AOD slag have the best impact strength among all tested Kalk-based briquettes.

• Heat treatment has positive influence on the impact strength of Kalk-based briquettes. Briquettes containing 90% Kalk and 10% AOD slag showed best impact strength after heat treatment, while pure Kalk briquettes showed second best impact strength after heat treatment and briquettes containing 80% Kalk and 20% AOD slag had worst impact strength among all heat treated Kalk briquettes.

• Kalk-based briquettes are not suitable to be exposed to open air.

• Briquettes containing 90% Kalk and 10% AOD slag heat treated at 850℃ remained 56.12% more initial weight compared with those heat treated at 500℃.

For Fly Ash-based briquettes:

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• Heat treatment improves the impact strength of briquettes containing 90% Fly Ash and 10% AOD slag and briquettes containing 80% Fly Ash and 20% AOD slag, but has little improvements on pure Fly Ash briquettes.

• For pure Fly Ash briquettes, the improvement of briquettes after exposure to open air was slightly bigger than heat-treated and non-treated briquettes. 7-day-exposed briquettes had similar impact strength as 20-day-exposed briquettes. However, both had better impact strength compared with 35-day-exposed briquettes.

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6 Limitations & Future Work

• Since only one kind of binder was investigated in this thesis work, different binding materials should be investigated to find out the best combination between raw material and binders.

• Only three simple kinds of recipes are investigated in this thesis work (pure waste product, 90% waste product with 10% binder, 80% waste product with 20% binder). More recipes should be tested to find out optimum recipe for different materials. • More experiments should be carried out to test other impact strength of the briquettes,

such as compression strength.

• The mechanism of heat treatment should be investigated to find out what happened during heat treatment and help to determine the best heat treatment procedure. • Melting experiment of CaO-containing material should be continued to investigate the

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7 Acknowledgement

First of all, I would like to express my deepest gratitude to my supervisor Ph.D. Candidate Tova Jarnerud and my co-supervisor Docent Andrey Karasev, who work at Division of Applied Process Metallurgy, Department of Material Science and Engineering, KTH Royal Institute of Technology. I appreciate the chance I had to work in such a creating group with you and I learned a lot through the strictness attitude you showed about scientific research. I would like to say thank you for the help you gave me during the experiments, and also the meticulously advice you gave during thesis writing process.

Special thanks to Yingshan Yao, fellow master student at KTH who participated in part of the experiment procedure. Also, thanks to the fellow Ph.D. students at KTH for giving me advices and help for the experiment.

I would also like to say thank you to those lovely people who attended my master thesis defence. Special thanks to Docent Chuan Wang from Swerea MEFOS and Gunnar Ruist from Outokumpu Avesta for travelling such a long way for the presentation.

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[7] W. Xia and Y. Yao, “Utilization of waste products from paper & pulp industry in the metal industry,” Unpublished Report, Stockholm, 2017.

[8] A. Hagelqvist, “Sludge from pulp and paper mills for biogas production,” DISSERTATION, Karlstad University Studies, Karlstad, 2013.

[9] P. Bajpai, “Chapter 2, Generation of Waste in Pulp and Paper Mills,” in Management of Pulp and Paper Mill Waste, Switzerland, Springer, 2015, pp. 9-10.

[10] J. M.Reckamp, “ Selective pyrolysis of paper mill sludge by using pretreatment processes to enhance the quality of bio-oil and biochar products,” Biomass and Bioenergy, vol. 71, pp. 235-244, 2014.

[11] E. Union, “Council Directive 1999/31/EC of 26 April 1999 on the landfill of waste,” 1999. [12] E. Union, “DIRECTIVE 2008/98/EC OF THE EUROPEAN PARLIAMENT AND OF THE

COUNCIL,” 2008.

[13] E. COMMISSION, “Roadmap to a Resource Efficient Europe,” Brussels, 2011.

[14] L. H.Buruberri, “Preparation of clinker from paper pulp industry wastes,” Journal of Hazardous Materials, vol. 286, pp. 252-260, 2015.

[15] M. Likon and P. Trebše, “Recent Advances in Paper Mill Sludge Management,” IntechOpen, 2012.

[16] M. Pervaiz, “Recycling of Paper Mill Biosolids: A Review on Current Practices and Emerging Biorefinery Initiatives,” CLEAN – Soil, Air, Water, vol. 43, no. 6, pp. 919-926, 2014.

[17] ParmilaDevi, “Simultaneous adsorption and dechlorination of pentachlorophenol from effluent by Ni–ZVI magnetic biochar composites synthesized from paper mill sludge,” Chemical

Engineering Journal, vol. 271, pp. 195-203, 2015.

[18] C. I.A.Ferreira, “Comparative adsorption evaluation of biochars from paper mill sludge with commercial activated carbon for the removal of fish anaesthetics from water in Recirculating Aquaculture Systems,” Aquacultural Engineering, vol. 74, pp. 76-83, 2016.

[19] N. R.Khalili, “Production of micro- and mesoporous activated carbon from paper mill sludge: I. Effect of zinc chloride,” Carbon, vol. 38, pp. 1905-1915, 2000.

[20] SATYENDRA, “LIMESTONE AND DOLOMITE FLUX AND THEIR USE IN IRON AND STEEL PLANT,” ISPAT DIGEST, 8 May 2013. [Online]. Available: http://ispatguru.com/limestone-and-dolomite-flux-and-their-use-in-iron-and-steel-plant/. [Accessed 15 April 2018]. [21] X. Weiqiang, “Converter refined slaging medium and slagging technique”. China Patent

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[22] W. Chuan, “The pulp industry's residual products can be valuable to the metal industry,” Swerea, 12 May 2017. [Online]. Available:

https://www.swerea.se/nyheter/massaindustrins-restprodukter-kan-bli-vardefulla-for-metallindustrin. [Accessed 23 May 2018].

[23] W. Chuan, “Utilization of Prganic Sludge in Metal Industrty (OSMet): VINNOVA UDI stage 1,” Unpublished Report, 2018.

[24] A. V. Karasev, “Lecture 3-Sulphur of molten iron and steel,” [unpublished slides], 2016. [25] L. Holappa, “On Physico‐Chemical and Technical Limits in Clean Steel Production,” Steel

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APPENDIX A – Detailed Data and Plots for Mesa-Based briquettes

MA (100% Mesa) Briquettes Heat Treated at 850℃

Detail drop test data of MA briquettes heat treated at 850℃

Number of

Drops MA1 MA2 MA3 Average 0 100.00% 100.00% 100.00% 100.00% 1 94.71% 96.60% 97.88% 96.40% 2 83.26% 92.51% 95.62% 90.46% 3 77.52% 80.99% 94.54% 84.35% 4 71.95% 74.57% 93.38% 79.97% 5 69.96% 72.91% 91.95% 78.28% 6 69.45% 70.92% 90.47% 76.94% 7 68.29% 64.83% 90.08% 74.40% 8 67.86% 64.21% 88.86% 73.64% 9 65.37% 63.60% 88.29% 72.42% 10 65.19% 63.51% 87.51% 72.07% 11 64.69% 63.46% 86.71% 71.62% 12 64.27% 63.36% 85.93% 71.19% 13 63.98% 63.25% 85.18% 70.81% 14 63.81% 63.21% 84.25% 70.42% 15 63.70% 63.17% 83.34% 70.07% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

MA1 MA2 MA3 Average

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MA (100% Mesa) Briquettes Without Heat Treatment

Detail drop test data of MA briquettes without heat treatment

Number

of Drops MA4 MA5 MA6 Average 0 100.00% 100.00% 100.00% 100.00% 1 26.12% 21.03% 41.27% 29.47% 2 11.11% 5.63% 5.04% 7.26% 3 9.46% 3.57% 2.98% 5.34% 4 1.69% 2.54% 0.78% 1.67% 5 0.57% 1.00% - 0.52% 6 - 0.33% - 0.11%

Weight loss trend of MA briquettes without heat treatment 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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MB (90% Mesa + 10% AOD slag) Briquettes Heat Treated at 850℃

Detail drop test data of MB briquettes heat treated at 850℃

Number of Drops MB1 MB2 MB3 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.32% 98.54% 96.49% 98.12% 2 98.38% 97.75% 95.61% 97.24% 3 97.89% 96.11% 92.12% 95.37% 4 97.17% 95.49% 91.64% 94.77% 5 97.03% 92.65% 91.02% 93.57% 6 95.96% 91.92% 87.91% 91.93% 7 92.76% 91.64% 87.45% 90.62% 8 92.35% 90.23% 85.46% 89.35% 9 91.96% 89.02% 82.66% 87.88% 10 90.95% 86.53% 81.95% 86.48% 11 90.17% 85.95% 81.59% 85.90% 12 88.61% 84.30% 81.08% 84.66% 13 87.85% 83.59% 78.98% 83.47% 14 86.54% 80.96% 78.68% 82.06% 15 86.54% 78.07% 78.26% 80.95% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops MB1 MB2 MB3 Average

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MB (90% Mesa + 10% AOD slag) Briquettes Heat Treated at 500℃

Detail drop test data of MB briquettes heat treated at 500℃

Number of Drops MB4 MB5 MB6 Average 0 100.00% 100.00% 100.00% 100.00% 1 95.03% 99.29% 54.75% 82.99% 2 50.01% 98.84% 20.35% 56.42% 3 46.52% 52.39% 19.22% 39.35% 4 37.06% 51.09% 17.67% 35.27% 5 29.27% 50.90% 17.44% 32.55% 6 28.97% 50.15% 17.39% 32.18% 7 28.76% 36.89% 17.27% 27.64% 8 22.88% 22.69% 13.93% 19.82% 9 22.81% 22.29% 13.66% 19.58% 10 13.61% 17.02% 13.55% 14.73% 11 13.40% 16.78% 13.43% 14.54% 12 13.33% 13.28% 9.37% 11.99% 13 12.51% 13.04% 4.37% 9.96% 14 12.47% 12.98% 4.34% 9.92% 15 12.40% 9.99% 2.65% 8.33% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops MB4 MB5 MB6 Average

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MB (90% Mesa + 10% AOD slag) Briquettes Without Heat Treatment

Detail drop test data of MB briquettes without heat treatment

Number of Drops MB7 MB8 MB9 Average 0 100.00% 100.00% 100.00% 100.00% 1 81.50% 42.13% 42.27% 55.30% 2 27.58% 14.09% 34.37% 25.35% 3 4.04% 6.96% 32.42% 14.48% 4 2.10% 4.20% 18.77% 8.36% 5 1.63% 1.83% 15.99% 6.48% 6 1.32% 0.21% 13.37% 4.97% 7 1.28% - 4.17% 1.82% 8 1.26% - 3.80% 1.69% 9 0.67% - 3.55% 1.41% 10 - - 0.46% 0.15% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops MB7 MB8 MB9 Average

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Non-Heat-Treated MB (90% Mesa + 10% AOD slag) Briquettes With 35 Days Exposure

Detail drop test data of MB briquettes with 35 days exposure

Number of Drops MB10 MB11 MB12 MB Average 0 100.00% 100.00% 100.00% 100.00% 1 98.13% 99.10% 37.67% 78.30% 2 50.80% 43.53% 16.37% 36.90% 3 47.91% 13.12% 4.87% 21.97% 4 20.53% 6.55% 3.46% 10.18% 5 9.98% 2.73% 3.11% 5.27% 6 3.12% 1.56% 1.76% 2.14% 7 2.36% 0.60% 0.36% 1.11% 8 1.06% 0.00% 0.00% 0.35% 9 0.81% 0.00% 0.00% 0.27%

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MC (80% Mesa + 20% AOD slag) Briquettes Heat Treated at 850℃

Detail drop test data of MC briquettes heat treated at 850℃

Number of Drops MC1 MC2 MC3 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.76% 99.26% 99.58% 99.53% 2 82.52% 91.02% 99.18% 90.91% 3 79.25% 87.81% 95.01% 87.36% 4 76.19% 81.85% 81.69% 79.91% 5 75.01% 81.04% 79.60% 78.55% 6 74.13% 78.56% 79.37% 77.35% 7 73.25% 75.99% 79.14% 76.13% 8 72.76% 75.47% 78.09% 75.44% 9 72.50% 74.06% 77.46% 74.67% 10 72.31% 72.65% 76.14% 73.70% 11 72.20% 71.75% 76.00% 73.32% 12 72.04% 71.40% 75.85% 73.10% 13 70.56% 68.25% 75.58% 71.46% 14 70.44% 67.76% 75.21% 71.14% 15 70.32% 66.81% 74.88% 70.67% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops MC1 MC2 MC3 Average

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MC (80% Mesa + 20% AOD slag) Briquettes Without Heat Treatment

Detail drop test data of MC briquettes without heat treatment

Number of

Drops M3AN M3BN M3CN M3N Average 0 100.00% 100.00% 100.00% 100.00% 1 43.62% 43.32% 49.83% 45.59% 2 24.68% 14.93% 48.80% 29.47% 3 20.09% 6.88% 17.93% 14.97% 4 19.71% 4.36% 11.66% 11.91% 5 14.97% 1.81% 4.87% 7.22% 6 9.60% 0.55% 4.48% 4.88% 7 5.69% - 1.72% 2.47% 8 5.30% - 0.46% 1.92% 9 1.61% - - 0.54% 10 1.27% - - 0.42% 11 1.04% - - 0.35% 12 0.63% - - 0.21% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e am in in g We ig h t Number of Drops MC4 MC5 MC6 Average

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APPENDIX B – Detailed Data and Plots for Kalk-Based briquettes

KA (100% Kalk) Briquettes Heat Treated at 850℃

Detail drop test data of KA briquettes heat treated at 850℃

Number of

Drops KA1 KA2 KA3 Average 0 100.00% 100.00% 100.00% 100.00% 1 86.74% 99.15% 88.38% 91.42% 2 85.34% 98.07% 86.41% 89.94% 3 39.25% 88.61% 85.78% 71.21% 4 38.63% 84.92% 39.81% 54.46% 5 37.96% 50.11% 39.43% 42.50% 6 30.29% 22.27% 33.47% 28.68% 7 24.84% 21.98% 36.97% 27.93% 8 23.99% 21.60% 28.40% 24.66% 9 23.32% 21.37% 7.62% 17.43% 10 21.66% 21.07% 7.44% 16.72% 11 21.09% 20.92% 6.58% 16.19% 12 20.50% 19.13% 5.99% 15.21% 13 18.34% 17.74% 4.89% 13.65% 14 17.68% 17.47% 4.74% 13.29% 15 17.17% 17.21% 4.69% 13.02% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

KA1 KA2 KA3 Average

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KA (100% Kalk) Briquettes Without Heat Treatment

Detail drop test data of KA briquettes without heat treatment

Number of

Drops KA4 KA5 KA6 K1N Average 0 100.00% 100.00% 100.00% 100.00% 1 14.96% 17.36% 18.92% 17.08% 2 2.59% 0.68% 2.32% 1.86% 3 0.53% - 0.27% 0.27% 0% 20% 40% 60% 80% 100% 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 R e m ai n in g We ig h t Number of Drops

KA4 KA5 KA6 Average

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KB (90% Kalk + 10% AOD slag) Briquettes Heat Treated at 850℃

Detail drop test data of KB briquettes heat treated at 850℃

Number of Drops KB1 KB2 KB3 Average 0 100.00% 100.00% 100.00% 100.00% 1 92.69% 99.51% 88.52% 93.57% 2 72.19% 98.94% 85.69% 85.61% 3 71.58% 98.53% 82.24% 84.12% 4 68.47% 98.10% 81.29% 82.62% 5 68.05% 61.12% 67.15% 65.44% 6 67.29% 55.35% 57.54% 60.06% 7 48.95% 54.39% 53.02% 52.12% 8 48.37% 52.13% 50.80% 50.44% 9 45.15% 51.49% 50.24% 48.96% 10 42.58% 48.36% 48.13% 46.36% 11 42.04% 47.54% 46.72% 45.43% 12 41.52% 47.15% 48.89% 45.86% 13 34.81% 46.15% 48.87% 43.28% 14 25.32% 45.76% 31.36% 34.14% 15 24.48% 45.04% 31.10% 33.54% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops KB1 KB2 KB3 Average

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KB (90% Kalk + 10% AOD slag) Briquettes Heat Treated at 500℃

Detail drop test data of KB briquettes heat treated at 500℃

Number of Drops KB4 KB5 KB6 Average 0 100.00% 100.00% 100.00% 100.00% 1 42.36% 38.06% 32.61% 37.68% 2 15.96% 12.43% 7.83% 12.07% 3 6.09% 4.42% 5.49% 5.33% 4 4.63% 1.21% 2.61% 2.82% 5 4.49% 0.21% 0.82% 1.84% 6 2.53% - - 0.84% 7 2.05% - - 0.68% 8 1.24% - - 0.41% 9 0.17% - - 0.06% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops KB4 KB5 KB6 Average

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KB (90% Kalk + 10% AOD slag) Briquettes Without Heat Treatment

Detail drop test data of KB briquettes without heat treatment

Number of Drops KB7 KB8 KB9 K2N Average 0 100.00% 100.00% 100.00% 100.00% 1 44.73% 25.19% 47.17% 39.03% 2 17.10% 14.60% 14.02% 15.24% 3 1.70% 2.89% 5.81% 3.47% 4 0.69% 0.19% 1.54% 0.81% 5 0.00% - 0.78% 0.26%

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KC (80% Kalk + 20% AOD slag) Briquettes Heat Treated at 850℃

Detail drop test data of KC briquettes heat treated at 850℃

Number of Drops KC1 KC2 KC3 Average 0 100.00% 100.00% 100.00% 100.00% 1 91.45% 99.35% 99.24% 96.68% 2 90.78% 44.84% 51.13% 62.25% 3 54.91% 16.26% 24.85% 32.01% 4 50.87% 16.16% 15.26% 27.43% 5 34.79% 16.05% 14.92% 21.92% 6 16.43% 15.90% 14.74% 15.69% 7 4.77% 14.76% 14.60% 11.38% 8 3.42% 14.56% 14.47% 10.82% 9 3.36% 14.25% 14.41% 10.67% 10 2.91% 14.09% 14.35% 10.45% 11 2.70% 13.92% 13.77% 10.13% 12 2.67% 13.06% 13.46% 9.73% 13 2.61% 8.17% 11.27% 7.35% 14 2.55% 7.17% 10.99% 6.90% 15 2.31% 7.04% 10.92% 6.76% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops KC1 KC2 KC3 Average

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KC (80% Kalk + 20% AOD slag) Briquettes Without Heat Treatment

Detail drop test data of KC briquettes without heat treatment

Number of Drops KC4 KC5 KC6 Average 0 100.00% 100.00% 100.00% 100.00% 1 53.52% 34.99% 45.17% 47.01% 2 38.38% 13.56% 25.47% 24.47% 3 12.39% 3.57% 10.41% 15.27% 4 4.09% 0.97% 2.61% 2.76% 5 1.15% 0.25% 0.59% 0.36% 6 0.36% 0.00% 0.12% 0.00% 0% 20% 40% 60% 80% 100% 0 2 4 6 8 10 12 14 R e m ai n in g We ig h t Number of Drops KC4 KC5 KC6 Average

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APPENDIX C – Detailed Data and Plots for Fly Ash-Based briquettes

FA (100% Fly Ash) Briquettes withoutHeat Treatment

Detail drop test data of KA briquettes without heat treatment

Number of

Drops FA1 FA2 FA3 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.41% 61.16% 99.84% 86.81% 2 85.82% 33.39% 92.13% 70.45% 3 83.47% 23.13% 63.08% 56.56% 4 65.60% 22.76% 62.81% 50.39% 5 62.33% 14.00% 61.96% 46.10% 6 61.16% 4.75% 59.93% 41.95% 7 41.09% 0.00% 57.68% 32.92% 8 37.67% 0.00% 53.40% 30.35% 9 19.10% 0.00% 26.91% 15.34% 10 7.06% 0.00% 26.16% 11.08% 11 0.00% 0.00% 22.42% 7.47% 12 0.00% 0.00% 20.55% 6.85% 13 0.00% 0.00% 16.80% 5.60%

Weight loss trend of FA briquettes without heat treatment 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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FA (100% Fly Ash) Briquettes Heat Treated at 850℃

Detail drop test data of FA briquettes heat treated at 850℃

Number of

Drops FA4 FA5 FA6 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.50% 99.32% 97.24% 98.69% 2 73.87% 65.90% 97.19% 78.99% 3 73.52% 65.78% 96.48% 78.60% 4 66.52% 21.33% 59.43% 49.09% 5 65.42% 18.08% 13.25% 32.25% 6 64.31% 13.13% 11.48% 29.64% 7 51.65% 6.39% 5.06% 21.03% 8 50.45% 0.00% 4.61% 18.35% 9 39.44% 0.00% 0.00% 13.15% 10 18.52% 0.00% 0.00% 6.17% 11 4.40% 0.00% 0.00% 1.47%

Figure A2 Weight loss trend of FA briquettes heat treated at 850℃ 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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FA (100% Fly Ash) Briquettes With 7 Days Exposure

Detail drop test data of FA briquettes with 7 Days Exposure

Number of

Drops FA8 FA9 FA10 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.51% 99.75% 99.21% 99.49% 2 99.67% 99.45% 98.07% 99.06% 3 98.67% 99.32% 97.97% 98.65% 4 97.90% 96.96% 80.48% 91.78% 5 97.76% 96.49% 41.64% 78.63% 6 96.68% 55.00% 41.39% 64.36% 7 96.32% 54.69% 29.12% 60.04% 8 95.99% 54.34% 29.00% 59.77% 9 95.73% 29.20% 28.32% 51.08% 10 94.12% 29.07% 27.75% 50.31% 11 93.75% 27.94% 27.24% 49.64% 12 93.30% 26.03% 24.89% 48.07% 13 92.70% 17.67% 24.78% 45.05% 14 47.61% 17.65% 12.30% 25.85% 15 47.24% 17.56% 12.22% 25.67% 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

FA8 FA9 FA10 FA Average

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Number of

Drops FA11 FA12 FA13 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.95% 99.56% 99.65% 99.72% 2 99.72% 99.60% 98.65% 99.32% 3 98.87% 99.18% 98.43% 98.83% 4 98.80% 98.63% 98.24% 98.56% 5 98.64% 98.09% 97.99% 98.24% 6 26.39% 97.40% 97.81% 73.87% 7 10.21% 97.05% 97.43% 68.23% 8 10.14% 96.62% 97.17% 67.97% 9 8.51% 66.50% 97.01% 57.34% 10 7.92% 61.68% 96.69% 55.43% 11 7.73% 15.72% 94.90% 39.45% 12 7.69% 15.50% 94.68% 39.29% 13 7.67% 12.94% 94.21% 38.27% 14 7.58% 12.80% 91.20% 37.19% 15 6.67% 4.40% 91.00% 34.02%

Figure A3 Weight loss trend of FA briquettes with 20 days exposure 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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Number of

Drops FA14 FA15 FA16 F Average 0 100.00% 100.00% 100.00% 100.00% 1 99.74% 99.53% 99.60% 99.62% 2 99.60% 99.42% 99.33% 99.45% 3 98.97% 98.28% 98.89% 98.71% 4 37.92% 97.81% 85.73% 73.82% 5 28.12% 96.77% 77.03% 67.31% 6 27.57% 96.01% 76.40% 66.66% 7 26.96% 95.00% 49.02% 56.99% 8 25.92% 45.82% 47.25% 39.67% 9 25.39% 43.70% 26.13% 31.74% 10 20.33% 25.95% 12.72% 19.67% 11 8.34% 25.36% 12.59% 15.43% 12 8.22% 23.68% 10.31% 14.07% 13 8.03% 18.38% 10.09% 12.16% 14 7.69% 16.97% 6.36% 10.34% 15 7.57% 14.99% 6.31% 9.62%

Weight loss trend of FA briquettes with 35 days exposure 0% 20% 40% 60% 80% 100% 0 3 6 9 12 15 R e m ai n in g We ig h t Number of Drops

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FB (90% Fly Ash + 10% AOD slag) briquettes Without Heat Treatment

Detail drop test data of FB briquettes without heat treatment

Number of Drops FB1 FB2 FB3 Average 0 100.00% 100.00% 100.00% 100.00% 1 99.20% 99.06% 99.32% 99.19% 2 53.07% 97.84% 98.69% 83.20% 3 28.51% 97.39% 33.51% 53.14% 4 27.41% 49.85% 14.03% 30.43% 5 21.62% 34.18% 13.33% 23.04% 6 21.17% 32.79% 6.47% 20.14% 7 18.52% 32.45% 0.00% 16.99% 8 13.33% 31.76% 0.00% 15.03% 9 5.84% 24.01% 0.00% 9.95% 10 4.14% 12.86% 0.00% 5.67% 11 3.69% 3.74% 0.00% 2.48% 12 1.30% 0.00% 0.00% 0.43%

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FB (90% Fly Ash + 10% AOD slag) Briquettes Heat Treated at 850℃

Detail drop test data of FB briquettes heat treated at 850℃

Number of Drops FB4 FB5 FB6 Average 0 100.00% 100.00% 100.00% 100.00% 1 98.03% 99.15% 99.47% 98.88% 2 97.93% 85.37% 98.77% 94.02% 3 93.72% 79.76% 98.24% 90.57% 4 93.24% 78.43% 96.26% 89.31% 5 77.98% 46.69% 95.09% 73.25% 6 76.97% 44.41% 94.13% 71.84% 7 53.62% 41.55% 93.33% 62.83% 8 52.87% 39.43% 60.19% 50.83% 9 52.07% 33.81% 59.55% 48.48% 10 51.91% 32.80% 58.48% 47.73% 11 31.12% 30.90% 17.88% 26.63% 12 30.64% 15.42% 7.31% 17.79% 13 29.63% 0.00% 0.00% 9.88% 14 25.69% 0.00% 0.00% 8.56% 15 11.60% 0.00% 0.00% 3.87%

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FB (90% Fly Ash + 10% AOD slag) Briquettes Heat Treated at 500℃

Detail drop test data of FB briquettes heat treated at 500℃

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FB (90% Fly Ash + 10% AOD slag) Briquettes With 7 Days Exposure to Open Air

Detail drop test data of FB briquettes with 7 days exposure to open air

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Number of Drops FB17 FB18 FB19 FB Average 0 100.00% 100.00% 100.00% 100.00% 1 99.25% 99.89% 99.96% 99.70% 2 98.90% 99.69% 99.80% 99.46% 3 97.06% 56.80% 99.56% 84.47% 4 96.38% 55.13% 98.97% 83.49% 5 96.04% 54.87% 40.99% 63.97% 6 95.13% 54.63% 27.59% 59.12% 7 94.84% 54.05% 26.71% 58.53% 8 63.36% 37.50% 24.90% 41.92% 9 62.68% 37.22% 17.57% 39.16% 10 19.41% 37.04% 9.64% 22.03% 11 19.17% 36.78% 9.55% 21.84% 12 19.07% 21.84% 9.04% 16.65% 13 18.94% 7.62% 5.36% 10.64% 14 14.23% 3.62% 3.73% 7.19% 15 14.20% 3.52% 3.66% 7.13%

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FC (80% Fly Ash + 20% AOD slag) Briquettes Without Heat Treatment

Detail drop test data of FC briquettes without heat treatment

Number of Drops FC1 FC2 FC3 FC Average 0 100.00% 100.00% 100.00% 100.00% 1 98.85% 98.37% 99.85% 99.03% 2 97.90% 97.05% 36.09% 77.01% 3 95.95% 96.47% 18.12% 70.18% 4 33.75% 47.03% 17.92% 32.90% 5 13.15% 19.48% 6.96% 13.20% 6 11.55% 16.04% 0.00% 9.20% 7 2.65% 7.15% 0.00% 3.27%

Initial evaluation of briquetting possibilities of CaO-containing paper production waste

Initial evaluation of briquetting

possibilities of CaO-containing

paper production waste

For use in metallurgical processes

XIA WEI

Abstract

Contents

1 Introduction

1.1 Social and Ethical Considerations

1.2 Pre-Study and Conclusion

2 Literature Review of Waste Treatment

3 Experimental Procedure

3.1 Materials for Drop Test

3.2 Briquetting Process

3.3 Heat Treatment of Briquettes

3.4 Exposure to Open Atmosphere

3.5 Drop Test Procedure

3.6 Melting Experiment

3.6.1 Materials for Melting Experiment

Graphite Crucible

Al

O

Crucible

Fire-Proof Brick

log 𝐿

= 𝑙𝑜𝑔

= −

3.7 General Information of Drop Test

4 Results and Discussion

4.1 Heat-Treated Briquettes vs. Non-Heat-Treated Briquettes

4.1.1 Mesa-Based Briquettes

4.1.2 Kalk-Based Briquettes

4.1.3 Fly Ash-Based Briquettes

4.2 Briquettes Heat Treated at 850℃ vs Briquettes Heat Treated at 500℃

4.3 Briquettes with Different Exposure Time to Open Atmosphere

4.3.1 35-Day-Exposed Briquettes vs Unexposed Briquettes

4.3.2 Impact of Different Exposure Time to Open Atmosphere (7days vs 20days vs

35days)

4.4 Melting Experiment

4.5 Overall Discussion

5 Conclusion

6 Limitations & Future Work

7 Acknowledgement

8 References

APPENDIX A – Detailed Data and Plots for Mesa-Based briquettes

APPENDIX B – Detailed Data and Plots for Kalk-Based briquettes

APPENDIX C – Detailed Data and Plots for Fly Ash-Based briquettes