A method for treating coke oven gas desulfurization by-product sulfur paste

Abstract

A method for processing a sulphur paste as a by-product from coke oven coal gas desulphuration, characterized in that a sulphur paste processing procedure comprises the steps of dissolving sulphur and removing impurities, decolouring and removing impurities, lowering the temperature and crystallizing, drying the product and the like; and a waste liquid treatment procedure comprises the steps of decoloring and removing impurities, concentrating a salt-containing filtrate under reduced pressure, separating ammonium thiocyanate, concentrating and crystallizing the ammonium thiocyanate ethyl alcohol filtrate, drying the ammonium thiocyanate product, separating ammonium sulphate, concentrating and crystallizing the ammonium thiosulphate filtrate, drying the ammonium thiosulphate product, and the like. The present invention can thoroughly process the sulphur paste and the sulphur-containing waste liquid, has a high product recovery, has no mixed salt or waste water discharge, and thus no secondary pollution, so that the process is clean and environmentally friendly. The present invention also has outstanding characteristics such as strong adaptability, high production flexibility, a high resource utilization rate and the like.

Description

technical field [0001] The invention belongs to the technical field of coking industry waste treatment. It specifically relates to a treatment method for coke oven gas desulfurization by-product sulfur paste, that is, a process for further purifying sulfur paste produced in the HPF or PDS desulfurization production process of a coking plant and performing harmless treatment of the purified sulfur-containing waste liquid . Background technique [0002] The coke oven gas produced during the coal coking process contains 5-8g / m 3 of hydrogen sulfide (H 2 S) and 1~1.5g / m 3 Hydrogen cyanide (HCN), the sulfur oxides and nitrogen oxides generated after its combustion seriously pollute the environment, and the above two gases are toxic substances. Therefore, at present, domestic coking enterprises are equipped with coke oven gas desulfurization and decyanation equipment, and the desulfurization and decyanation processes used by the equipment can be divided into two categories: ox...

AI Technical Summary

Problems solved by technology

At present, the purification of sulfur can be roughly divided into two categories: (1) the purification method of molten sulfur (CN200910153102.6, CN200910150565.7, CN200410020529.6, CN00256049.6); (2) the organic solvent purification method (CN200310114627.1, CN200810229462.5), although the above patents all claim that high-purity sulfur can be obtained, comprehensive analysis from the perspectives of environmental protection, energy and economy, the above-mentioned processes all have high energy consumption, large pollution in the purification process and low extraction rate, especially sulfur paste Harmful substances (mainly ammonium thiocyanate, ammonium thiosulfate) and other impurities contained in the purified waste liquid cannot be harmlessly treated, so the waste liquid after sulfur paste purification still causes environmental pollution and other disadvantages

[0005] There are currently three main treatment methods for the waste liquid after desulfurization by-product sulfur paste purification and HPF desulfurization waste liquid: the first is to use the principle of co-saturated multi-component system phase diagram to concentrate multiple times and crystallize the thiocyanate in a step-by-step manner Separation and purification of ammonium and ammonium thiosulfate (CN201110180361.5, CN200810128357.2). Since the solubility difference between ammonium thiocyanate and ammonium thiosulfate is not large, the process is cumbersome and requires high crystallization concentration and temperature control. The salt purity is low, the economic benefits are poor, and it is not suitable for wastewater solutions with high ammonium sulfate content; the second is to oxidize the ammonium thiosulfate in the desulfurization liquid to ammonium sulfate through a catalyst, and then fractionally crystallize and purify ammonium thiocyanate and sulfuric acid Ammonium (CN201210147582.7, CN2007101395747, Japanese Patent Publication No. 55-126531), the disadvantage of this method is that copper salt needs to be regenerated at high temperature when using copper salt to purify ammonium thiocyanate, and ammonium thiosulfate with high economic value cannot be purified. The benefit is poor, the copper salt lost in the purification process becomes a new source of pollution, and more industrial wastewater is discharged; the third is to convert all the ammonium salt in the wastewater into ammonium sulfate under high temperature and pressure and under the action of a catalyst for recovery ( Japanese Patent Publication No. 57-7852), this method requires high equipment conditions, high operating costs, and the economic value of ammonium sulfate obtained by oxidation is low, and general enterprises cannot use this method

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