Detailed explanation of domestic steel slag utilization

Slag is the waste produced by the metallurgical industry, one of the industrial solid waste, which produces 8% to 15% of crude steel production, by 2012 the world steel slag discharge about 180 million t? China's steel slag production amount with The rapid development of the iron industry has been increasing rapidly. Therefore, the problem of the treatment and resource utilization of iron and steel enterprises' waste residue has been paid more and more attention. The national “Eleventh Five-Year” development plan pointed out that the comprehensive utilization rate of steel slag should be more than 86%. Basically realize “zero emissions” However, the current status of comprehensive utilization in China is far from the plan, especially the utilization rate of converter steel slag, which is known as “inferior cement clinker”, is only 10%-20%. Domestic steel enterprises slag produced not in time, resulting in a large slag occupation of land, environmental pollution? unavailable but not solid waste slag, which contains large amounts of steel slag, calcium oxide, magnesium oxide and iron components can be utilized?

1 steel slag for metallurgical raw materials

01 recycling scrap steel

The steel slag contains a large amount of iron, and the average mass fraction is about 25%. The metal iron accounts for about 10% of the magnetic separation. The scrap steel of each grade can be recovered, and most of the steel slag containing high iron grade is used as steelmaking and refining. Iron raw materials.

02 steel slag used as sintered material

Since 40%~50% of CaO is contained in the converter steel slag, it can be used as a sintering ingredient instead of part of limestone . It can not only recycle residual steel, iron oxide, calcium oxide, magnesium oxide, manganese oxide and rare elements (V, Nb, etc. in steel slag). And so on, and can increase the drum index and agglomeration rate and facilitate the sintering of the ball and increase the sintering speed, the heat generated by the oxidation of Fe and FeO in the steel slag can reduce the consumption of the sinter fuel.

03 steel slag used as blast furnace flux

The converter steel slag contains 40%~50% CaO and 6%~10% MgO. It can be used as a blast furnace cosolvent instead of limestone and dolomite to save ore resources. In addition, due to limestone (CaCO3) and dolomite [ The process of decomposing CaMg(CO3)2] into CaO and MgO requires energy, while Ca and Mg in steel slag exist in the form of oxides, thus saving a lot of heat energy.

04 steel slag used as steel slag return slag

Steel slag return to converter smelting can reduce raw material consumption and reduce total slag? Can smelting itself promote slag and shorten smelting time?

2 steel slag for road engineering

01 steel slag production of cement and concrete admixture

Slag contains tricalcium silicate (of C3S) having a hard cementitious water, dicalcium silicate (C2S) aluminum and iron salts and other minerals activity, in line with the characteristics of cement? Can be used for the production of cement clinker free, less cooked Raw materials for cement and cement admixtures.

Steel slag cement has excellent characteristics such as wear resistance, high flexural strength, corrosion resistance and frost resistance.

02 steel slag instead of gravel and fine aggregate

Steel slag crushed stone has the advantages of high strength, rough surface, good wear resistance and durability, great capacity, good stability, and strong bonding with asphalt . It also has low temperature crack resistance compared with ordinary gravel, so it can be widely used in roads. Engineering backfilling? Steel slag as railway track slag, has the characteristics of not interfering with the railway system telecommunications work, good electrical conductivity, etc. Because the steel slag has good water seepage and drainage, the gelling component can make it slab into a large block. Road construction in swamps and beaches.

3 new building materials engineering applications

01 new concrete

Through the grinding process, the activity of the industrial waste is improved and used as a concrete admixture to enter the sixth component of the concrete, the fine mineral admixture. Fine grinding not only reduces the slag powder particles, increases its specific surface area, further hydrates the f-CaO in the slag powder to improve the stability of the slag powder, but also changes the lattice structure and surface physicochemical properties of the steel slag. The grinding energy is converted into the internal energy and surface energy of the slag powder, and the gelation property of the steel slag is improved. The high-performance concrete cementing material can be prepared by using the stimulating property between the steel slag micropowder and the blast furnace ore powder and the appropriate activator. At the same time, according to different use requirements, road concrete (high tensile strength, good wear resistance, bending resistance and impermeability), marine concrete (good water seepage, drainage, high marine organism adhesion rate), etc. Series products.

02 carbonized steel slag construction materials

The main factors causing poor stability of steel slag are free calcium oxide and free magnesium oxide, all of which can react with CO2, and the steel slag will rapidly harden in a short time in a CO2-rich environment. With this property, steel slag can be utilized. The steel slag bricks are reused in different buildings. The important significance is that the physical and chemical properties of the carbonized curing materials have been greatly improved. At the same time, the CO2 emissions are effectively controlled and the greenhouse effect is improved.

4 steel slag microcrystalline glass granite , glass ceramic

Slag Glass has since developed in the 1960s to form in many countries a large-scale production? Cheng Jin trees to reducing slag as the main raw materials developed aesthetic appearance of the glass-ceramic granite? Chen Huijun, etc. with pulverized coal ash and slag For the main raw materials, we have developed glass-ceramics with calcium and iron-gray as the main crystal phase.

5 steel slag application in environmental engineering

The high alkalinity and large specific surface area of ​​steel slag can be used to treat wastewater?

Studies have shown that steel slag chemical precipitation and adsorption with? In the slag treatment Chromium-containing wastewater, the removal rate of 99% Cr? Slag processing wastewater containing Zinc, zinc removal rate of more than 98%, the treated wastewater GB897888 reach wastewater discharge standards? slag treatment of mercury-containing waste water, the mercury removal efficiency reached 90.6%? the research results provide an effective way to solve the mercury in marine pollution?

Phosphorus-containing slag may also be used to treat other waste water containing heavy metal wastewater and?

6 steel slag application in agriculture

Steel slag can be used as alkaline slag in acidic soil. Among them, CaO and MgO can improve soil quality. Steel slag with high phosphorus content can also be used in phosphorus-deficient alkaline soil and enhance the ability of crops to resist pests and diseases. Silicon is the growth demand of rice. The largest element, steel slag with SiO2 content higher than 15% can be used as silicon fertilizer?

7 other uses

Steel slag can also produce non-burning bricks, foundry sand, cement expansion agent, fluid sand hardener, etc. It can also be used as a sulfur dioxide absorber instead of limestone and lime as tailings produced by crushing iron. The product can be used for the transformation of saline-alkali or as a cement additive according to local conditions, and can form a complete steel slag recycling industrial chain according to local conditions.

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