Strengthen the resource utilization of metallurgical solid waste and promote the green development of metallurgical industry

In recent years, China's economy has sustained rapid growth, coal, electricity, metallurgy, chemical and other industries have developed rapidly, and the industrial level has been continuously improved, the scale has been continuously expanded, and the capacity has been continuously enhanced, but the ensuing pressure on the environment and resources has also been increasing. Among them, the discharge of bulk metallurgical solid waste has affected and restricted the high-quality development of industrial economy, and put forward new requirements for the comprehensive utilization of metallurgical enterprises' resources.

The new concept of green development proposed in the "13th Five-Year Plan" has brought metallurgical solid waste treatment to a new height, and the advanced technology of comprehensive utilization of metallurgical solid waste has also been included in the encouraged category in the guidance catalogue for industrial structure adjustment in 2019. Therefore, promoting the comprehensive utilization of metallurgical solid waste resources and improving the comprehensive utilization level is an inevitable choice to achieve the green development of metallurgical industry. Recovery of valuable metals At present, the recycling of solid waste in metallurgical industry is mainly based on the recovery of valuable metals, supplemented by the development of high value-added products, and multi-direction comprehensive development.

Metallurgical solid waste contains a variety of other metals, often can be extracted gold, silver, cobalt, antimony, palladium, platinum, etc., some content can reach or even exceed the grade of industrial deposits, and the value of some recovered rare precious metals even exceeds the value of the main metal. For example, the copper slag is collected in the recovery chamber, and the copper particles can be recovered through the reduction treatment technology; There is 10%-45% iron in the red mud, and a large amount of iron can be recovered to obtain high-grade iron-making concentrate, from which aluminum, titanium, vanadium, chromium, manganese and a variety of rare earth elements and trace radioactive elements can be extracted. Coal ash and coal gangue contain iron, molybdenum, germanium, vanadium, uranium, aluminum and other metals, and also have the value of recovery.

Some metallurgical solid waste because of its high metal composition, can be smelted enterprises reprocessing, but some do not have such characteristics, at this time it is necessary to strengthen cooperation with other industries to improve the overall utilization of metallurgical solid waste. Building materials industry The building materials industry plays a very important role in the disposal of metallurgical solid waste. Some advanced enterprises stimulate the activity of steel slag tailings by grinding fine, instead of cement for concrete construction projects, can reduce the cracks caused by the hydration heat of concrete, improve the late strength of concrete and wear resistance, freeze resistance, corrosion resistance. China also uses red mud to produce a variety of types of cement, the production of ordinary Portland cement also has high strength, sulfate resistance and other properties, in the field of engineering construction use effect is very good.

In addition, slag is also used to produce high-performance glass-ceramics. Slag glass-ceramics are made of metallurgical slag, tailings and other industrial wastes and natural minerals as the main raw materials, and a certain amount of auxiliary raw materials such as nucleation agent and flux are introduced, which are made by batching, melting, molding, annealing, crystallization and other processes. Slag glass-ceramics are not only rich in raw materials, but also have some excellent properties and the characteristics of consuming industrial waste slag which are unmatched by other materials. Agricultural use of metallurgical solid waste production or instead of agricultural fertilizer has broad prospects, many waste residues contain high silicon, calcium and various trace elements, some also contain phosphorus, so it can be used as agricultural fertilizer. Such as fly ash, blast furnace slag, steel slag and ferroalloy slag can be applied to farmland as silicon calcium fertilizer; Steel slag can be used as raw material for producing calcium magnesium phosphate fertilizer when the content of phosphorus is high. Red mud can also be widely used in the production of silicon calcium fertilizer.

The utilization of metallurgical slag in ceramic industry is a way of bulk and high value resource utilization. The inert components, heavy metals, free calcium oxide or alkali metals in metallurgical slag in ceramics are transformed into beneficial components in ceramics, and the mechanical properties of ceramic products are better than the requirements of national standards, and they also have other excellent characteristics such as anti-wear, corrosion resistance and consolidation of heavy metals. At present, industrial production has been successfully achieved in the preparation of metallurgical slag ceramics. It can be said that at present, China has the technical strength of using industrial solid waste to prepare ceramic materials, and the technology has obvious advantages.

Environmental protection industry Metallurgical solid waste can also be used in environmental engineering. The results show that steel slag has chemical precipitation and adsorption. In the study of steel slag treatment of wastewater containing chromium, the removal rate of chromium reaches 99%. In the study of steel slag treatment of zinc-containing wastewater, the removal rate of zinc is more than 98%, and the treated wastewater meets the comprehensive discharge standard of GB897888. In the study of treating mercury-containing wastewater with steel slag, the removal rate of mercury reached 90.6%. The results of this study provide an effective way to solve Marine mercury pollution. Steel slag can also be used to treat wastewater containing phosphorus and other heavy metals. In addition, the high alkalinity of steel slag is conducive to the suppression of Marine red tide, which has a positive significance for Marine ecological governance.

China has carried out a lot of work on the comprehensive utilization of metallurgical solid waste and made many achievements, but the realization of the comprehensive utilization of metallurgical solid waste is not limited to the building materials industry, agriculture, ceramics industry and so on. The treatment and utilization of metallurgical solid waste involves a number of interdisciplinary fields, and more experts and enterprises are needed to participate in it.