Construction of comprehensive treatment of mine solid waste

In 2005, the State Environmental Protection Administration, the Ministry of Land and Resources, the Ministry of Health issued the "Mining ecological environment protection and pollution prevention technology Policy", for the mine solid waste proposed to vigorously promote the comprehensive utilization of mineral processing solid waste technology, including: (1) tailings recycling and co-associated minerals and valuable elements recovery technology; ② The use of tailings processing production of building materials and products technology, such as cement additives, tailings brick, etc.; (3) Promote the technology of using tailings and waste rock as fillers to fill goaf or subsidence areas; (4) Using coal preparation slime to develop bio-organic fertilizer technology.

Let's talk about these aspects in detail:

1. Recycle useful metals from tailings. One of the products of separation operations in beneficiation, the part with the lowest content of useful target components is called tailings. Under the current technical and economic conditions, it is not appropriate to further improve sorting. However, with the development of production science and technology, the useful target components may also have the economic value of improving recycling. Tailings are not completely useless materials, often contain components that can be used for other purposes, and can be comprehensively utilized. Achieve no waste discharge. It is necessary to make full use of mineral resources and protect the ecological environment. The 11 tailings ponds of 7 large iron ore concentrators in a northeast region of China, with an annual discharge of 27 million tons of tailings, accumulated 770 million tons of tailings by May 2017, containing 8%~16% iron, and recovered iron concentrate (containing 54%~65% iron) and middle ore (containing 35%~40% iron) for cement plants as additives after the construction of the reconcentration workshop. The Nanyuan Iron Mine used the magnetic-gravity separation process to concentrate 5 million tons of tailings, and recovered 407,800 tons of iron concentrate with a grade of 56.71% and a recovery rate of 42.94%. Yongping Copper Mine daily treatment of 2000 tons of tailings, tailings by the combined process of heavy magnetic, heavy, floating and heavy separation step by step, the production of schetungstine concentrate 399.3 tons, sulfur concentrate 1584 tons, annual output value of 6.648 million yuan, annual profit of 1.728 million yuan; Dazhi Lvtongshan has recovered the tailings for many times. In the tailings after floating copper magnetic separation, iron concentrate is selected by the strong magnetic separation process and then the gold copper concentrate and iron concentrate with higher gold and silver content are selected by the re-grinding floating one weight one magnetic separation process. Gold copper concentrate 21.34g/t, silver 100g/t, copper 16.58g/t, the recovery rates were 64.81%, 18.16% and 53.66%, respectively. Some of the above successful cases we can learn from.

2. Use tailings to produce building materials

(1) Using tailings to make bricks. Iron tailings can be made into fire-free bricks, wall and floor decorative bricks. Maanshan Mine Research Institute has successfully made free brick by using iron ore tailings from Qidashan and Waitoushan. Jiangxi Copper Company Yinshan lead-zinc mine is used to produce autoclaved silicate brick because of its stable chemical composition of tailings. Dandong Institute of Building Materials used gold mine slag as the main raw material, adding some clay material with good plasticity, and made a new type of building decoration material - waste slag decorative brick by sintering. The use of copper and tungsten tailings to make bricks has also been successfully developed.

(2) The use of tailings to produce cement. Cement is made by two grinding and one firing process, and the strength of cement depends on the firing of clinker and the mineral composition in the clinker. Clinker is generally composed of tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium ferroaluminate, among which tricalcium silicate and tricalcium aluminate play an important role in the early strength of cement. Dicalcium silicate, tetracalcium ferroaluminate and tricalcium silicate played an important role in the later strength. Tricalcium silicate is the main mineral in cement clinker (about 50%). Tailings are used to produce cement, which is to use some trace elements in tailings to affect the formation of clinker and mineral composition.

(3) The use of tailings to produce new glass materials. Using high iron and aluminum tailings as the main raw material, the surface glass made by melting is black, shiny and uniform, no bubbles, no defects. (4) The use of tailings to produce building glass-ceramics. Tailings glass-ceramics granite was made from Damiao Iron Mine tailings and waste rock. The compressive strength, flexion strength, gloss and acid-alkali resistance of the finished products reached or exceeded that of natural granite. Using copper tailings as the main raw material, the glass-ceramics of copper tailings with high strength, wear-resistance and corrosion resistance have been developed through industrial tests to replace marble, granite and ceramic tiles. In addition, the use of tungsten tailings to develop glass-ceramics. (5) Use tailings to produce other building materials. Using the tailings of Dagushan concentrator mixed with cement, lime and other raw materials, the aerated concrete is made with light weight and good moisture retention. In addition, iron tailings can be used as basic materials for roadbed in large quantities.