中国有色冶金

Blast furnace gas ash is one of the main solid emissions from steel companies, rich in valuable elements and a valuable secondary resource.Due to the different raw materials of various enterprises, the composition of blast furnace gas ash is complex and has its own characteristics, with major elements intermingled. A single treatment process cannot meet the treatment requirements of blast furnace gas ash.This article aims to address the high content of K, Zn, and Pb in the blast furnace gas ash of Baotou Steel, and based on the analysis of the composition and phase of the raw materials, uses a water washing-potassium extraction-carbothermic reduction-dilute acid leaching process to extract and separate K, Zn, and Pb. The following main conclusions are drawn.The zinc and lead in the gas ash mainly exist in the form of oxides, while the potassium and sodium elements mainly exist in the form of chloride and sulfate salts. Various elements are intermingled and combined, resulting in a complex structure;The optimal process parameters for extracting potassium by water washing are a water washing time of 20minutes, a temperature of 90℃, and a liquid-solid ratio of 10∶1. Under these conditions, the potassium dissolution rate can reach 84.4%. The remaining potassium is solidified in aluminum silicate structures formed by doping multiple elements and cannot be dissolved;The optimal experimental conditions for carbothermic reduction of lead and zinc enrichment are 8% carbon content, 1400℃ reduction temperature, and 3h reduction time. Under these conditions, the zinc content in the reduction slag decreases from 3.61% to below 0.005%, and the lead content decreases from 1.28% to below 0.005%. The removal rate is above 90%;The lead-rich zinc powder was leached with 10% dilute sulfuric acid, and the zinc was dissolved and separated in the form of sulfate, resulting in a insoluble residue rich in elemental lead with a lead content of 77.22%.In actual production, chlorine gas can be used to dry waste sulfuric acid instead of 10% sulfuric acid in this process flow, which not only improves the environmental protection of the process, but also realizes the resourceful reuse of waste sulfuric acid.