Technical method for recycling potassium, sodium and zinc from blast furnace bag ash

Abstract

The invention relates to a technical method for recycling potassium, sodium and zinc from blast furnace bag ash. The raw material of the method is the blast furnace bag ash, and the method aims to realize recycling of potassium, sodium and zinc and cyclic utilization of iron-containing slag in a steel plant. The method comprises the process of recycling potassium and sodium through water washing,the process of reducing and volatilizing zinc and the process of recycling zinc through a wet method. The method specifically includes the steps that after the blast furnace bag ash is subjected to water washing, a filtrate containing potassium chloride and sodium chloride is obtained, and the filtrate saturated with potassium chloride or sodium chloride is purified and subjected to fractional crystallization to obtain KCl and NaCl products; the filtrate not saturated with potassium chloride or sodium chloride is subjected to the water washing step again, after the water washing residues are dried, the water washing residues, a reduction agent and an adhesive are evenly mixed and granulated according to a certain mass ratio, then high-temperature reduction and volatilization of zinc are carried out in a reduction device, and the iron-containing slag is recycled in the steel plant; and zinc-rich dust recycled in a flue gas recycling system is leached, purified and electrolytically deposited to obtain metal zinc products, and electrolyte is recycled in the leaching step. According to the process flow, high-value utilization of the blast furnace bag ash and cyclic utilization of the blast furnace bag ash in the steel plant are simultaneously realized, and energy conservation and emission reduction of steel enterprises are promoted.

Description

technical field [0001] The invention belongs to the field of resource utilization of waste, and in particular relates to the technological process of using fire-wet combined method, recovering potassium and sodium through water washing, reducing and volatilizing to obtain iron-containing reducing slag, and recovering zinc by wet method to realize resource recycling of blast furnace bag ash . Background technique [0002] Blast furnace bag ash is dust collected from blast furnace gas dry-type bag treatment, and is a high-temperature mixture of iron ore powder, coke, lime and other ironmaking furnace materials. Table 1 shows the chemical composition of 1-4# blast furnace bag ash in a steel plant. It can be seen from the table that the blast furnace bag ash is mainly composed of Fe, C, Zn, K, Na, Cl, Ca, Si, Al and other elements, and the iron content About 27-37% (average content 31.85%), zinc content 2.1-4.6% (average content 3.51%), potassium content about 1-5% (average 3.5...

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Problems solved by technology

[0006] (1) Direct discharge and stockpiling may easily cause environmental pollution and waste of resources;

[0007] (2) Direct utilization, return to sintering or pelletizing, which is adopted by many domestic iron and steel enterprises, but its harmful impurities such as K, Na, Zn, etc. are relatively high, and mixing them into sintering or pelletizing will reduce the utilization factor of the blast furnace and cause coke Ratio increases, affecting the life of the blast furnace;

Therefore, the problem of direct return of blast furnace bag ash to the sintering system is that harmful elements such as K, Na, Zn in the sintering raw materials do not leave the path of the sintering process, resulting in cyclic enrichment, which will lead to excessively high content of harmful elements in the sinter. After entering the blast furnace, the harmful elements in the blast furnace will exceed the standard, which will cause a series of hazards to the blast furnace, cause the coke ratio of the blast furnace to increase, and affect the life of the blast furnace

[0010] However, so far no one has studied the technological process of K, Na, and Zn recovery in bagged blast furnace ash, which has led to the problem that the blast furnace bagged ash has not been used in high value and it is difficult to circulate in the steel plant

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