The metallurgical sludge of the steel plant mainly includes: blast furnace gas mud, converter dust and dust and ash.
During the steel making process, about 2% of the raw materials added to the converter will be converted into dust, and the amount of converter dust generated is about 20 kg/ton. Steelmaking dust is mainly composed of iron oxide, accounting for 70% to 95%, and other oxide impurities (such as CaO, ZnO, etc.) account for 5% to 30%. Converter steelmaking dust is generally used as a raw material for sintering, but zinc is a harmful element in the iron making process. Because it is easy to form a furnace in the process of blast furnace smelting, it affects the flow of charge and gas, so the converter dust is in the recycling process. In the middle, the fine ore and the C and Zn-rich tail mud can be recovered by the beneficiation method. Adding OG mud suspension to the sintering mixture is beneficial to the granulation of the mixture. With the increase of the OG mud dosage, the 1mm particle size ratio of the mixture is rapidly reduced, which is beneficial to improve the gas permeability of the mixture, increase the yield, reduce the cost and protect the mixture. surroundings.
The composition of the blast furnace gas mud is mainly about 20% of iron oxide, 23% of carbon, 1% to 5% of zinc, and more oxides such as CaO, SiO2 and Al2O3. The amount of blast furnace dust generated is about 25 kg/t. The blast furnace gas mud particles are finer, and less than 200 mesh accounts for more than 90%. The blast furnace gas mud is characterized by high content of zinc, iron, carbon, moisture, fine particles, and zinc is mainly present in smaller particles. The blast furnace gas and gas ash can be extracted by using hydraulic separation and beneficiation method to extract Zn-rich and C-rich tail mud as resources.
At present, the recycling rate of metallurgical dust in large enterprises in China can reach 100%. The process and technology of converter mud, dust removal ash and gas mud are at a relatively advanced level, which can bring good economic benefits to enterprises.
The process of comprehensive utilization of metallurgical sludge is as follows:
(1) Dry process of converter mud and dust removal ash
Converter mud, dust removal ash → sintering return mine → mixed material processing plant.
(2) Converter mud wet process
Converter mud → mixing tank → pipeline → sintering batching belt → converter mud drying + iron oxide scale + chemical binder → stirring and mixing → pressurizing into balls → drying in the furnace → pellets.
(3) Gas mud utilization process
Gas mud → re-election → iron fine powder → sintering plant → zinc-containing mud → fire method to extract zinc.
Steelmaking sludge is a by-product of dust removal from oxygen top-blown converters, and this resource is very precious. The chemical composition fluctuates greatly, the iron content is high, the basic oxide content is high, and the particle size is fine. The sludge can be used as a raw material for sintering and pelletizing, and can exchange part of the iron-containing raw material, and combines a small amount of binder and solvent. Reduce costs and reduce the role of steel plant sewage.
Sludge is a good iron raw material, the following methods of use:
1. As the ingredients directly return to the sintering and utilization, it has a great impact on the environment, easy to form a group alone, mixing is not easy, affecting the effectiveness of comprehensive utilization.
2. Pipeline transportation to the sinter plant for shotcrete utilization, the steelmaking sludge can be concentrated to a certain solid concentration at a short distance, and the pipeline is sent to the sintering as a substitute for the sintering make-up water.
3. The steel slag powder pellets are mixed and then extruded into a sludge pellet by a molding agent to be used as a steelmaking slag coolant, and a good effect is obtained. The state attaches great importance to environmental protection, and attaches importance to the treatment of converter sludge generated by steel enterprises. The growth of energy shortage price affects the development of the steel industry, and it is inevitable to find new ways and means.