Industrial Solid Waste Recycling in Western China

In this chapter, the general and industrial types of solid wastes are defined and illustrated. Several aspects of the industrial solid wastes are discussed, such as sources, classification, characteristics, and properties. Also, the pollution and techniques of solid waste treatment and disposal are discussed. The industrial solid wastes can be classified according to their hazards, industries, and chemical composition. Four basic forms of industrial wastes (i.e., solid, semisolid, gaseous, and liquid) as defined in the relevant legislation and administration are involved in the discussion. The industrial solid wastes generated in China are relatively consistent in composition and physical states with a large fraction of hazard compounds. Most of these industrial solid wastes are from mineral processing, coal combustion, and metallurgy. The large amount of multi-type industrial solid wastes has a high possibility of adverse impact on the environment and human health. The pollution can be controlled by prevention and comprehensive reuse of these wastes. Some of the prescribed industrial solid wastes can be treated by marine disposal and landfilling. Finally, the current status of industrial solid waste used is investigated.

This chapter mainly discusses the magnesium (Mg) slag generated in silicon thermic reduction of magnesium by Pidgeon process. Fluoride and fine dust in the slag and also the huge quantity of the slag (six to seven times of the magnesium produced) cause a big problem of environmental pollution, which can be eliminated by different technologies. First, it is discussed about the mechanism of the slag dust generation, the pellets disintegration, experimental results for slag volume stabilization, and dust controlled by adding several mineralizers. The second part of this chapter discusses the behavior of fluoride in Mg slag by Pidgeon process through a pilot trial facility, followed by the description of the utilization of F-free mineralizers in place of calcium fluoride (CaF₂) in magnesium production for the elimination of fluoride contamination. The last part discusses the utilization of stabilized magnesium slag instead of lime as a fluxing medium for steel smelting and the use of the mixture of magnesium slag and manganese residue to make sulphoaluminate cement clinker.

With the rapid development of the economy in China, manganese metal is increasingly required for fabrication of alloys aiming for construction of national infrastructure. However, the pollution generated by manganese industry became increasingly alarming. There are three types of pollutants issued from electrolytic manganese industry: solid waste, waste gases, and wastewater. The solid waste mainly includes manganese residues generated from acid immersion, chrome residues from wastewater treatment, and anode sludge from electrolytic processes. In this chapter, the physical and chemical properties of manganese metal, manganese ore, manganese metal production, and electrolytic manganese residue (EMR) treatment were introduced and discussed. EMR represents the filter acid sludge generated during production of electrolytic manganese metal after addition of manganese carbonate concentrate into sulfuric acid, containing large amounts of hazardous substances. The environmental EMR pollution due to electrolytic manganese industry became particularly serious. Therefore, EMR was well discussed, and technologies dealing with comprehensive treatments and recycling of EMR were proposed and discussed.

This chapter introduces the sources, characteristics, and utilization of acidic residue produced in lead and zinc production processes. Apart from some major and minor components (such as CaSO₄, CaF₂, Fe₂O₃, ZnO), hazardous elements, including As, Cd, Pb, Cu, Sn, In, Hg, and Cr, are traced and analyzed. Tessier’s sequential extraction procedure is employed for the fractionation of the hazardous elements, and leaching toxicity is assessed according to the standard methods. Based on these results, solidification and stabilization of the hazardous elements are studied with various approaches, including cement solidification, melting solidification, chemical reagent solidification, and fixation of plastic materials. In particular, solidification of Pb with magnesium slag is studied. As a highlight of this chapter, study of fly-ash-based geopolymer for the solidification of waste acidic residue and fuming slag and for fixation of hazardous elements is described. The beneficial outcomes from blending waste acidic residue and fuming slag in the geopolymer production are introduced, and the great performances of the geopolymer products are characterized. As a consequence, the target of “treating waste with waste” is satisfied, thus providing an environmentally friendly technology for the treatment of hazardous materials for the local businesses in China.

This chapter introduces the nature, composition, physicochemical properties, and classification of fly ash. It discusses the research status and progress of the comprehensive utilization of fly ash at home and abroad in terms of the applications of fly ash in areas such as building materials, mine filling, industrial wastewater treatment, flue gas desulfurization, and agriculture. In addition, this chapter describes the extraction of high-value components from fly ash.

The deposit volume of steel slag in China exceeds 400 million tons, leading to the occupation of a large area of land and serious environment pollution. However, the current utilization rate of steel slag in China is only about 21%, which is far behind that of developed countries. Recycling and reusing these solid wastes are essential, not only for conserving metals and mineral resources but also for protecting the environment. The physical and chemical characteristics of steel slag are summarized, and the pretreatment progress of steel slag in steel industries as recycled raw material was introduced. The utilization aspects (circulation in metallurgical industry, cement additive and concrete admixture, materials for wastewater or gas treatment, construction materials, and fertilizer in agriculture production, and raw materials of glass and ceramics) are introduced.

Carbide slag (acetylene sludge) is the industrial residue, which is discharged when the hydrolysis of calcium carbide is undertaken to prepare acetylene. The slag mainly consists of Ca(OH)₂. If the carbide slag is stacked on the spot, it may pollute water resources near the stacking field. Additionally, the drying of carbide slag generates dust, which pollutes the atmosphere. Therefore, cleaner production and sustainable use of resources are difficult and focus on research in China. At present, the comprehensive utilization of carbide slag includes several methods. One of the methods involving large consumption of carbide slag is the production of cement. Second, the application of carbide slag as a desulfurizer in wet flue gas desulfurization system can also treat wastes. Moreover, carbide slag is used to produce ordinary chemical products and prepare nanocalcium carbonate.