包钢高炉瓦斯灰中钾锌铅元素的提取研究

Study on extraction of potassium,zinc and lead from blast furnace gas ash of Baotou Steel

高炉瓦斯灰是钢铁企业的主要固体排放物之一,富含有价元素,是宝贵的二次资源。由于各企业原料不同,高炉瓦斯灰成分复杂且各有特点,主要元素互相掺杂,单一处理工艺已无法实现对高炉瓦斯灰的处理需求。本文针对包钢高炉瓦斯灰K、Zn、Pb成分较高的特征,在对原料进行成分、物相分析的基础上采用水洗提钾-碳热还原-稀酸浸出工艺进行了K、Zn、Pb的提取分离试验,得到以下主要结论。瓦斯灰中的锌、铅主要以氧化物形式存在,钾、钠元素则是主要以氯化盐和硫酸盐的形式存在,各种元素相互掺杂结合,结构复杂;水洗提钾的最佳工艺参数为水洗时间20 min、温度90℃、液固比10∶1,此条件下钾溶出率可达84.4%,余下部分钾在多种元素掺杂形成的铝硅酸盐类结构中被固化而无法溶出;碳热还原富集铅锌的最佳试验条件为配碳量8%、还原温度1 400℃、还原时间3 h,此条件下,还原渣中锌含量由3.61%降至0.005%以下,铅含量由1.28%降低至0.005%以下,去除率均在90%以上;采用10%稀硫酸浸出富铅锌粉,锌以硫酸盐的形式溶解分离,进而得到富含单质铅的难溶渣,铅含量为77.22%。实际生产中,可以采用氯气干燥废硫酸代替本工艺流程中10%硫酸,不仅可以提高工艺环保性,还实现废硫酸的资源化再利用。

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 20 minutes,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 3 h 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.