Review of Comprehensive Utilization of Metallurgical Solid Waste

**3**

shown in **Figure 1**.

**Chapter 1**

*Yingyi Zhang*

Introductory Chapter:

Metallurgical Solid Waste

**1. Utilization status of metallurgical solid waste resource**

The sustainable development of resources and energy is an inevitable trend of social development. With the rapid development of metallurgical industry, a large amount of metallurgical solid waste is produced. However, a lot of metallurgical solid wastes have not been timely and effectively recycled, resulting in serious problems of environmental pollution and resource wastage, such as heavy metal pollution in air, water, soil, and plant system. According to the characteristics of metallurgical industry, this book introduces the main types, sources, and characteristics of metallurgical solid waste. The application and treatment methods of blast furnace slag, converter slag, and electric furnace slag in building materials and ceramics industry are mainly introduced. The comprehensive utilization technology of Bayer process-produced red mud and converter sludge was also investigated. Blast furnace slag (BFS) is a by-product of iron-making, which is formed by the combination of iron ore with limestone flux. When the molten slag is rapidly cooled by water, a large amount of granulated and amorphous blast furnace slag is produced, and the physical and chemical properties of these slags mainly depend on the production process. It is worth noting that a lot of water and heat are wasted in this process. The main chemical components of these slags are silica (SiO2), alumina (Al2O3), and lime (CaO), which are the main components of cement and CaO-Al2O3-SiO2 (CAS) glass ceramics [1, 2]. Therefore, the granulated blast furnace slag (GBFS) is usually used as feedstock for cement and glass ceramics manufacturing. The CaO content of blast furnace slag is about 35–56% [3], which can hydrate with water to form cementitious pozzolanic reaction products. When these slags are ground to a finer size, they can be utilized in the production of Portland slag cement [4]. The typical TEM micrograph of hydrated Portland cement (a) and photograph of the glass-ceramics (b) just fabricated from blast furnace slag are

Steel slags are by-products of steel production, which are produced during the electric arc furnace process in steel-making, converter steel-making, and the secondary refining of steel, respectively [7]. In the process of steel-making, steel slag production accounts for about 15% of steel output. The steel slag annual production worldwide is about 130 million tons which are mainly electrical arc furnace slag (EAF), basic oxygen furnace (BOF) slags, and ladle furnace basic slag (LFS) [8]. The main chemical components of steel slag include silica (SiO2), alumina (Al2O3), lime (CaO), magnesia (MgO), ferrous oxide (FeO), and hematite (Fe2O3), as shown in **Table 1**. The mineral components of steel slag mainly consist of olivine, hydraulic calcium silicate (*β*-Ca2SiO4 (C2S), Ca3SiO5 (C3S)), non-hydraulic calcium silicate (*γ*-Ca2SiO4 (C2S), CaSiO3 (CS)), tetra-calcium aluminoferrite (C4AF), dicalcium ferrite (C2F), and free CaO/MgO [15, 16]. As we all know, C2S and C3S are the main

### **Chapter 1**

## Introductory Chapter: Metallurgical Solid Waste

*Yingyi Zhang*

### **1. Utilization status of metallurgical solid waste resource**

The sustainable development of resources and energy is an inevitable trend of social development. With the rapid development of metallurgical industry, a large amount of metallurgical solid waste is produced. However, a lot of metallurgical solid wastes have not been timely and effectively recycled, resulting in serious problems of environmental pollution and resource wastage, such as heavy metal pollution in air, water, soil, and plant system. According to the characteristics of metallurgical industry, this book introduces the main types, sources, and characteristics of metallurgical solid waste. The application and treatment methods of blast furnace slag, converter slag, and electric furnace slag in building materials and ceramics industry are mainly introduced. The comprehensive utilization technology of Bayer process-produced red mud and converter sludge was also investigated.

Blast furnace slag (BFS) is a by-product of iron-making, which is formed by the combination of iron ore with limestone flux. When the molten slag is rapidly cooled by water, a large amount of granulated and amorphous blast furnace slag is produced, and the physical and chemical properties of these slags mainly depend on the production process. It is worth noting that a lot of water and heat are wasted in this process. The main chemical components of these slags are silica (SiO2), alumina (Al2O3), and lime (CaO), which are the main components of cement and CaO-Al2O3-SiO2 (CAS) glass ceramics [1, 2]. Therefore, the granulated blast furnace slag (GBFS) is usually used as feedstock for cement and glass ceramics manufacturing. The CaO content of blast furnace slag is about 35–56% [3], which can hydrate with water to form cementitious pozzolanic reaction products. When these slags are ground to a finer size, they can be utilized in the production of Portland slag cement [4]. The typical TEM micrograph of hydrated Portland cement (a) and photograph of the glass-ceramics (b) just fabricated from blast furnace slag are shown in **Figure 1**.

Steel slags are by-products of steel production, which are produced during the electric arc furnace process in steel-making, converter steel-making, and the secondary refining of steel, respectively [7]. In the process of steel-making, steel slag production accounts for about 15% of steel output. The steel slag annual production worldwide is about 130 million tons which are mainly electrical arc furnace slag (EAF), basic oxygen furnace (BOF) slags, and ladle furnace basic slag (LFS) [8]. The main chemical components of steel slag include silica (SiO2), alumina (Al2O3), lime (CaO), magnesia (MgO), ferrous oxide (FeO), and hematite (Fe2O3), as shown in **Table 1**. The mineral components of steel slag mainly consist of olivine, hydraulic calcium silicate (*β*-Ca2SiO4 (C2S), Ca3SiO5 (C3S)), non-hydraulic calcium silicate (*γ*-Ca2SiO4 (C2S), CaSiO3 (CS)), tetra-calcium aluminoferrite (C4AF), dicalcium ferrite (C2F), and free CaO/MgO [15, 16]. As we all know, C2S and C3S are the main

#### **Figure 1.**

*TEM micrograph of hydrated Portland cement (a) and photograph of the glass-ceramics (b) just fabricated from blast furnace slag [5, 6].*


#### **Table 1.**

*The main chemical compositions of steel slag (wt%).*

components of cement. Therefore, the steel-making slag also has certain cementitious properties and is used as feedstock for cement manufacturing, which is widely used in the construction industry. **Figure 2** shows the application of electric furnace slag concrete in construction.

Red mud (bauxite residue) is an alkaline solid waste residue generated from the Bayer process [17]. Presently, when producing a ton of alumina via Bayer process, about 0.8–2.0 t of red mud residues are produced, which mainly depends on the properties of raw material and production process conditions [18]. The global annual production of high-alkalinity red mud is about 120 million tons, and the global accumulation of red mud is about 2.7 billion tons [19]. The typical chemical compositions and mineralogical components of red mud are shown in **Table 2**. It can be seen that the red mud has a high pH or alkalinity, the aluminum compounds mainly consist of gibbsite (Al(OH)3), aluminous goethite (α-(Fe,Al)OOH), boehmite (AlOOH) or diaspore (AlOOH), and the iron oxide mainly consists of hematite (Fe2O3) and aluminous goethite (*α*-(Fe,Al)OOH). However, large quantities of red mud are discarded as waste, and have not been effectively developed and utilized. This leads to serious soil, air, and water pollution and takes up a lot of space [20]. At present, most of the red mud is directly placed in landfill, deep sea, and storage in settling ponds, as shown in **Figure 3**. Despite the harmful impact that these methods pose on our environment, the risks of failure of a poorly engineered storage dam can result in even greater social and economic damage. In addition, the

**5**

red mud has a high concentration of aluminum compound, sodium aluminate, and iron oxide sodium, which limits the application of red mud in cement and ceramic industry (**Tables 2** and **3**). Therefore, the comprehensive utilization of red mud

residue is an urgent problem in alumina industry.

*Typical views of the red mud (a) and red mud dam (b).*

*Introductory Chapter: Metallurgical Solid Waste DOI: http://dx.doi.org/10.5772/intechopen.83587*

*The application of EAF slag concrete in pavements [7].*

**Composition/ wt%**

Al2O3 5–30% Aluminous

TiO2 0.3–15% Hematite (iron

SiO2 3–50% Tricalcium

**Mineralogical name**

goethite

oxide)

aluminate

Titanium dioxide

Calcium carbonate

*Chemical composition and mineralogical components of red mud (wt%).*

Fe2O3 5–60% Sodalite 3Na2O·3Al2O3·6SiO2·Na2SO4 4–40%

CaO 2–20% Silica SiO2 5–20%

Na2O 1–10% Boehmite AlO(OH) 0–20%

**Chemical formula Composition/**

α-(Fe,Al)OOH 10–30%

3CaO·Al2O3·6H2O 2–20%

Muscovite K2O·3Al2O3·6SiO2·2H2O 0–15%

Gibbsite Al(OH)3 0–5% Kaolinite Al2O3·2SiO2·2H2O 0–5%

Fe2O3 10–30%

TiO2 2–15%

CaCO3 2–10%

**wt%**

**Figure 2.**

**Table 2.**

**Figure 3.**

**Chemical name**

*Introductory Chapter: Metallurgical Solid Waste DOI: http://dx.doi.org/10.5772/intechopen.83587*

#### **Figure 2.**

*Recovery and Utilization of Metallurgical Solid Waste*

components of cement. Therefore, the steel-making slag also has certain cementitious properties and is used as feedstock for cement manufacturing, which is widely used in the construction industry. **Figure 2** shows the application of electric furnace

*TEM micrograph of hydrated Portland cement (a) and photograph of the glass-ceramics (b) just fabricated* 

**Reference Type CaO SiO2 Al2O3 MgO Fe2O3** [9] BOFS 39.08 12.47 6.87 10.57 19.48 [10] 61.21 24.92 1.83 4.89 3.04 [11] 47.7 13.3 3.0 6.4 24.4 [12] EAFS 38.8 14.1 6.7 3.9 20.3 [13] 24.4 15.4 12.2 2.9 — [9] LFS 57.55 6.21 23.17 5.04 3.55 [14] 50.5–57.5 12.6–19.8 4.3–18.6 7.5–11.9 1.6–3.3 [12] 42.5 31.9 22.9 12.6 1.1

Red mud (bauxite residue) is an alkaline solid waste residue generated from the Bayer process [17]. Presently, when producing a ton of alumina via Bayer process, about 0.8–2.0 t of red mud residues are produced, which mainly depends on the properties of raw material and production process conditions [18]. The global annual production of high-alkalinity red mud is about 120 million tons, and the global accumulation of red mud is about 2.7 billion tons [19]. The typical chemical compositions and mineralogical components of red mud are shown in **Table 2**. It can be seen that the red mud has a high pH or alkalinity, the aluminum compounds mainly consist of gibbsite (Al(OH)3), aluminous goethite (α-(Fe,Al)OOH), boehmite (AlOOH) or diaspore (AlOOH), and the iron oxide mainly consists of hematite (Fe2O3) and aluminous goethite (*α*-(Fe,Al)OOH). However, large quantities of red mud are discarded as waste, and have not been effectively developed and utilized. This leads to serious soil, air, and water pollution and takes up a lot of space [20]. At present, most of the red mud is directly placed in landfill, deep sea, and storage in settling ponds, as shown in **Figure 3**. Despite the harmful impact that these methods pose on our environment, the risks of failure of a poorly engineered storage dam can result in even greater social and economic damage. In addition, the

**4**

slag concrete in construction.

*The main chemical compositions of steel slag (wt%).*

**Figure 1.**

**Table 1.**

*from blast furnace slag [5, 6].*

*The application of EAF slag concrete in pavements [7].*


#### **Table 2.**

*Chemical composition and mineralogical components of red mud (wt%).*

#### **Figure 3.**

*Typical views of the red mud (a) and red mud dam (b).*

red mud has a high concentration of aluminum compound, sodium aluminate, and iron oxide sodium, which limits the application of red mud in cement and ceramic industry (**Tables 2** and **3**). Therefore, the comprehensive utilization of red mud residue is an urgent problem in alumina industry.


**Table 3.**

*The chemical composition of red mud (wt%).*

## **2. Conclusions**

The sustainable development of resources and energy is an inevitable trend of social development. The comprehensive utilization of metallurgical solid waste is still a worldwide problem. Because of the limitations of current technology and consumption levels, a large amount of metallurgical solid waste has not been exploited effectively. The granulated blast furnace slag and steel slags are usually used as feedstock for cement and glass ceramics manufacturing. However, the traditional water quenching slag process wastes a lot heat of slag, polluted environment, and consumed water resources. Therefore, it is very important to develop technology for the utilization of waste heat from blast furnace slag and steel slag. Industrial storage is not the only way to solve the problem of comprehensive utilization and pollution of red mud. The recovery of valuable metals from red mud faces many technical problems, which seriously hinder the development of the metallurgical industry. In addition, applying red mud as construction material like cement or soil ameliorant faces the problem of Na, Cr, and As leaching into the environment. So, we must reduce the recycling process costs and energy consumption, promote the recovery of valuable metals, optimize complex processes, and develop new processes.

#### **Acknowledgements**

This work was supported by the National Key Research and Development Program of China (2017YFB0603800 & 2017YFB0603802) and the National Natural Science Foundation of China (No.51604049).

### **Author details**

Yingyi Zhang School of Metallurgical Engineering, Anhui University of Technology, Maanshan, Anhui Province, P. R. China

\*Address all correspondence to: zhangyingyi@cqu.edu.cn

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**7**

*Introductory Chapter: Metallurgical Solid Waste DOI: http://dx.doi.org/10.5772/intechopen.83587*

[1] Itoh T. Rapid discrimination of the character of the water-cooled blast furnace slag used for Portland slag cement. Journal of Materials Science. 2004;**39**(6):2191-2193. DOI: 10.1023/B:J Performance of fiber-reinforced EAF slag concrete for use in pavements. Construction and Building Materials. 2017;**149**:629-638. DOI: 10.1016/j.

conbuildmat.2017.05.174

[8] Zomeren AV, VanderLaan SR, Kobesen HBA, Huijgen WJJ, Comans RNJ. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure. Waste Management. 2011;**31**(11):2236-2244. DOI: 10.1016/j.wasman.2011.05.022

[9] Mahoutian M, Chaallal O, Shao Y. Pilot production of steel slag masonry blocks. Canadian Journal of Civil Engineering. 2018;**45**(7):537-546. DOI:

[10] Ghouleh Z, Guthrie RIL, Shao Y. High-strength KOBM steel slag binder activated by carbonation. Construction and Building Materials. 2015;**99**:175-183. DOI: 10.1016/j. conbuildmat.2015.09.028

[11] Waligora J, Bulteel D, Degrugilliers P, Damidot D, Potdevin JL, Measson M. Chemical and mineralogical characterizations of LD converter steel slags: A multi-analytical techniques approach. Materials Characterization. 2010;**61**(1):39-48. DOI: 10.1016/j.

10.1139/cjce-2017-0603

matchar.2009.10.004

[12] Tossavainen M, Engstrom F, Yang Q, Menad N, Lidstrom Larsson M, Bjorkman B. Characteristics of steel slag under different cooling conditions. Waste Management. 2007;**27**(10):B1335-B1344. DOI: 10.1016/j.wasman.2006.08.002

[13] Luxan MP, Sotolongo R, Dorrego F, Herrero E. Characteristics of the slags produced in the fusion of scrap steel by electric arc furnace. Cement and Concrete Research. 2000;**30**(4):517-519. DOI: 10.1016/S0008-8846(99)00253-7

[2] Zhang WT, He F, Xie JL, Liu XQ, Fang D, Yang H, et al. Crystallization mechanism and properties of glass ceramics from modified molten blast furnace slag. Journal of Non-Crystalline Solids. 2018;**502**:164-171. DOI: 10.1016/j.

[3] Kumar S, Kumar R, Bandopadhyay A, Alex TC, Kumar BR, Das SK, et al. Mechanical activation of granulated blast furnace slag and its effect on the properties and structure of Portland slag cement. Cement & Concrete Composites. 2008;**30**(8):679-685. DOI: 10.1016/j.cemconcomp.2008.05.005

[4] Sekhar DC, Nayak S. Utilization of granulated blast furnace slag and cement in the manufacture of compressed stabilized earth blocks. Construction and Building Materials. 2018;**166**:531-536. DOI: 10.1016/j.

[5] Taylor R, Richardson IG, Brydson RMD. Composition and microstructure of 20-year-old ordinary Portland cement-ground granulated blastfurnace slag blends containing 0 to 100% slag. Cement and Concrete Research. 2010;**40**(7):971-983. DOI: 10.1016/j.cemconres.2010.02.012

[6] Gao HT, Liu XH, Chen JQ, Qi JL, Wang YB, Ai ZR. Preparation of glass-ceramics with low density and high strength using blast furnace slag, glass fiber and water glass. Ceramics International. 2017;**44**(6):6044-6053. DOI: 10.1016/j.ceramint.2017.12.228

[7] Fuente-Alonso JA, Ortega-López V, Skaf M, Aragón Á, San-José JT.

conbuildmat.2018.01.125

MSC.0000017785.44922.30

**References**

jnoncrysol.2018.08.024

*Introductory Chapter: Metallurgical Solid Waste DOI: http://dx.doi.org/10.5772/intechopen.83587*

## **References**

*Recovery and Utilization of Metallurgical Solid Waste*

**6**

**Author details**

**Acknowledgements**

**2. Conclusions**

*The chemical composition of red mud (wt%).*

**Table 3.**

Anhui Province, P. R. China

Yingyi Zhang

provided the original work is properly cited.

\*Address all correspondence to: zhangyingyi@cqu.edu.cn

Natural Science Foundation of China (No.51604049).

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

School of Metallurgical Engineering, Anhui University of Technology, Maanshan,

This work was supported by the National Key Research and Development Program of China (2017YFB0603800 & 2017YFB0603802) and the National

The sustainable development of resources and energy is an inevitable trend of social development. The comprehensive utilization of metallurgical solid waste is still a worldwide problem. Because of the limitations of current technology and consumption levels, a large amount of metallurgical solid waste has not been exploited effectively. The granulated blast furnace slag and steel slags are usually used as feedstock for cement and glass ceramics manufacturing. However, the traditional water quenching slag process wastes a lot heat of slag, polluted environment, and consumed water resources. Therefore, it is very important to develop technology for the utilization of waste heat from blast furnace slag and steel slag. Industrial storage is not the only way to solve the problem of comprehensive utilization and pollution of red mud. The recovery of valuable metals from red mud faces many technical problems, which seriously hinder the development of the metallurgical industry. In addition, applying red mud as construction material like cement or soil ameliorant faces the problem of Na, Cr, and As leaching into the environment. So, we must reduce the recycling process costs and energy consumption, promote the recovery of valuable metals, optimize complex processes, and develop new processes.

**Reference Fe2O3 Al2O3 CaO SiO2 TiO2 Na2O MgO Cr2O3 V2O5 LOI** [21] 43.59 18.45 11.38 6.0 5.54 1.82 0.35 0.27 0.17 11.7 [22] 28.30 17.67 20.88 8.34 7.34 2.29 0.65 — — 13.88 [17] 54.8 14.8 2.5 6.4 3.7 4.8 — — 0.38 9.5 [23] 32.52 18.42 16.74 8.34 6.75 3.59 — — — 13.64

[1] Itoh T. Rapid discrimination of the character of the water-cooled blast furnace slag used for Portland slag cement. Journal of Materials Science. 2004;**39**(6):2191-2193. DOI: 10.1023/B:J MSC.0000017785.44922.30

[2] Zhang WT, He F, Xie JL, Liu XQ, Fang D, Yang H, et al. Crystallization mechanism and properties of glass ceramics from modified molten blast furnace slag. Journal of Non-Crystalline Solids. 2018;**502**:164-171. DOI: 10.1016/j. jnoncrysol.2018.08.024

[3] Kumar S, Kumar R, Bandopadhyay A, Alex TC, Kumar BR, Das SK, et al. Mechanical activation of granulated blast furnace slag and its effect on the properties and structure of Portland slag cement. Cement & Concrete Composites. 2008;**30**(8):679-685. DOI: 10.1016/j.cemconcomp.2008.05.005

[4] Sekhar DC, Nayak S. Utilization of granulated blast furnace slag and cement in the manufacture of compressed stabilized earth blocks. Construction and Building Materials. 2018;**166**:531-536. DOI: 10.1016/j. conbuildmat.2018.01.125

[5] Taylor R, Richardson IG, Brydson RMD. Composition and microstructure of 20-year-old ordinary Portland cement-ground granulated blastfurnace slag blends containing 0 to 100% slag. Cement and Concrete Research. 2010;**40**(7):971-983. DOI: 10.1016/j.cemconres.2010.02.012

[6] Gao HT, Liu XH, Chen JQ, Qi JL, Wang YB, Ai ZR. Preparation of glass-ceramics with low density and high strength using blast furnace slag, glass fiber and water glass. Ceramics International. 2017;**44**(6):6044-6053. DOI: 10.1016/j.ceramint.2017.12.228

[7] Fuente-Alonso JA, Ortega-López V, Skaf M, Aragón Á, San-José JT.

Performance of fiber-reinforced EAF slag concrete for use in pavements. Construction and Building Materials. 2017;**149**:629-638. DOI: 10.1016/j. conbuildmat.2017.05.174

[8] Zomeren AV, VanderLaan SR, Kobesen HBA, Huijgen WJJ, Comans RNJ. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure. Waste Management. 2011;**31**(11):2236-2244. DOI: 10.1016/j.wasman.2011.05.022

[9] Mahoutian M, Chaallal O, Shao Y. Pilot production of steel slag masonry blocks. Canadian Journal of Civil Engineering. 2018;**45**(7):537-546. DOI: 10.1139/cjce-2017-0603

[10] Ghouleh Z, Guthrie RIL, Shao Y. High-strength KOBM steel slag binder activated by carbonation. Construction and Building Materials. 2015;**99**:175-183. DOI: 10.1016/j. conbuildmat.2015.09.028

[11] Waligora J, Bulteel D, Degrugilliers P, Damidot D, Potdevin JL, Measson M. Chemical and mineralogical characterizations of LD converter steel slags: A multi-analytical techniques approach. Materials Characterization. 2010;**61**(1):39-48. DOI: 10.1016/j. matchar.2009.10.004

[12] Tossavainen M, Engstrom F, Yang Q, Menad N, Lidstrom Larsson M, Bjorkman B. Characteristics of steel slag under different cooling conditions. Waste Management. 2007;**27**(10):B1335-B1344. DOI: 10.1016/j.wasman.2006.08.002

[13] Luxan MP, Sotolongo R, Dorrego F, Herrero E. Characteristics of the slags produced in the fusion of scrap steel by electric arc furnace. Cement and Concrete Research. 2000;**30**(4):517-519. DOI: 10.1016/S0008-8846(99)00253-7

[14] Setién J, Hernández D, González JJ. Characterization of ladle furnace basic slag for use as a construction material. Construction and Building Materials. 2009;**23**(5):1788-1794. DOI: doi. org/10.1016/j.conbuildmat.2008.10.003

[15] Maslehuddin M, Sharif AM, Shameem M, Ibrahim M, Barry MS. Comparison of properties of steel slag and crushed limestone aggregate concretes. Construction and Building Materials. 2003;**17**(2):105-112. DOI: 10.1016/S0950-0618(02)00095-8

[16] Tsakiridis PE, Papadimitriou GD, Tsivilis S, Koroneos C. Utilization of steel slag for Portland cement clinker production. Journal of Hazardous Materials. 2008;**152**(2):805-811. DOI: 10.1016/j.jhazmat.2007.07.093

[17] Samal S, Ray AK, Bandopadhyay A. Proposal for resources, utilization and processes of red mud in India-a review. International Journal of Mineral Processing. 2013;**118**(30):43-55. DOI: 10.1016/j.minpro.2012.11.001

[18] Liu WC, Yang JK, Xiao B. Review on treatment and utilization of bauxite residues in China. International Journal of Mineral Processing. 2009;**93**(3-4):220-231. DOI: 10.1016/j. minpro.2009.08.005

[19] Klauber C, Gräfe M, Power G. Bauxite residue issues: II options for residue utilization. Hydrometallurgy. 2011;**108**(1-2):11-32. DOI: 10.1016/j. hydromet.2011.02.007

[20] Li RB, Zhang TA, Liu Y, Lv GZ, Xie LQ. Calcification-carbonation method for red mud processing. Journal of Hazardous Materials. 2016;**316**:94-101. DOI: 10.1016/j.jhazmat.2016.04.072

[21] Samouhos M, Taxiarchou M, Pilatos G, Tsakiridis PE, Devlin E, Pissas M. Controlled reduction of red mud by H2 followed by magnetic separation. Minerals Engineering.

2017;**105**(1):36-43. DOI: 10.1016/j. mineng.2017.01.004

[22] Liu DY, Wu CS. Stockpiling and comprehensive utilization of red mud research progress. Materials. 2012;**5**(7):1232-1246. DOI: 10.3390/ ma5071232

[23] Li XB, Wi X, Liu W, Liu GH, Peng ZH, Zhou QS, et al. Recovery of alumina and ferric oxide from Bayer red mud rich in iron by reduction sintering. Transactions of Nonferrous Metals Society of China. 2009;**19**(5):1342-1347. DOI: 10.1016/S1003-6326(08)60447-1

**9**

Section 2

Comprehensive Utilization

of Blast Furnace Slag

## Section 2
