Secondary zinc oxide slurry treating light concentration SO2 flue gas method and device thereof

Abstract

The invention relates to a method which adopts secondary zinc oxide slurry to treat SO2 off-gas having low concentration, as well as the device thereof, and has the following steps: water or filtrate is used for preparing slurry together with secondary zinc oxide; the slurry is delivered to the liquid collecting trough of a torrential scrubber; the slurry in the liquid collecting trough is pumped into the reverse spraying tower nozzle of the torrential scrubber through a circulation pump, the slurry is delivered to an oxidation tower through an agitator pump, sulfuric acid is added from the top part of the oxidation tower, compressed air is input from the bottom end, the oxidated slurry is discharged into an acid hydrolysis trough, and the acid hydrolysis slurry is pumped into a box filter press through a pressing filter pump for realizing solid-liquid separation; the secondary zinc oxide slurry is adopted to absorb the SO2 in the smelter off-gas, so as to enable the processed off-gas to reach standard discharge, and reduce the pollution to the environment caused by the SO2 off-gas of a lead-zinc smeltery, thereby having the advantages of high operating rate, good working condition, low equipment failure rate, high desulfurization efficiency, etc., and enabling the sulfur, zinc and lead resources to be comprehensively utilized.

Description

technical field [0001] The invention belongs to the non-ferrous metal smelting industry, and in particular relates to a method of treating low-concentration SO2 using secondary zinc oxide slurry. 2 Treatment of low-concentration SO by secondary zinc oxide slurry in flue gas 2 Method and device for flue gas. Background technique [0002] There are hundreds of flue gas desulfurization methods, but they can be divided into three categories: wet method, semi-dry method and dry method according to the process flow. The wet method is the most widely used and the most mature technology in the world. my country's exhaust gas desulfurization technology has been studied in the sulfuric acid industry and nonferrous metallurgical industry as early as the 1950s. 2 Research on flue gas treatment began in the 1970s. But so far, the relatively mature flue gas desulfurization technologies in my country are mainly double subtraction method and lime method, and these two methods are widely...

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Problems solved by technology

[0003] The disadvantage of the double alkali method is that calcium sulfite is generated during the regeneration of sodium sulfite absorbed and generated. Although most of it can be oxidized to calcium sulfate, there is always a certain amount of calcium sulfite that has not been oxidized, which affects the reuse of gypsum; Lost in the filter cake, resulting in the consumption of part of the absorption liquid, increasing operating costs; third, the regenerated absorption liquid contains calcium ions, which must be softened, otherwise it will easily cause fouling and blockage of equipment and pipelines

Disadvantage of the lime method: CaSO produced by direct desulfurization of milk of lime 3 1 / 2H 2 O and CaCO 4 2H 2 The solubility of O is extremely low, and it is easy to reach supersaturated crystallization, resulting in scaling. In severe cases, equipment and pipelines will be blocked and unable to operate; second, the calcium sulfate generated by desulfurization contains a small amount of calcium sulfite, which affects recycling and is easy to cause damage to the equipment during storage. Secondary pollution of the environment

This method has the following disadvantages: (1) due to the addition of oxygen inhibitor in the circulating slurry, the oxidation of zinc sulfite to zinc sulfate is prevented, so that the solid content in the circulating slurry tends to increase, and the solid content is as high as 18-22 %, it is very easy to cause solid deposits and blockages in some parts of equipment and pipelines; (2) due to the small solubility of zinc sulfite, scaling is easy to form in some parts of the turbulent ball tower (such as grid pores) (3) when adopting air oxidation method or acid hydrolysis method to handle press filter residue, press filter residue needs to be through pulping earlier, just could enter oxidation tank or acid hydrolysis tank, increased equipment investment; (4) when processing with air oxidation method When pressing the filter residue, the residual oxygen inhibitor in the filter residue is not conducive to air oxidation

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