Method for reducing pH value of fly ash-coproduced calcium silicate filler for papermaking and purifying flue gas simultaneously

Abstract

The invention relates to a method for reducing a pH value of a fly ash-coproduced calcium silicate filler for papermaking and purifying flue gas simultaneously. The method comprises the following steps of: preparing hydrous calcium silicate suspension liquid by using fly ash as a raw material; feeding the hydrous calcium silicate suspension liquid into an absorption tower, mixing the hydrous calcium silicate suspension liquid with flue gas in the absorption tower, and drying and absorbing; detecting the purified flue gas; enabling the purified flue gas to enter a flue and discharging the purified flue gas if the total volume percent of CO2 and SO2 is reduced to be lower than 0.001%; or else, returning the purified flue gas to a flue gas pipeline for circulating purification; analyzing the alkalinity of treated calcium silicate; if the pH value is more than 9, continuing mixing calcium silicate with the flue gas in the absorption tower, and drying and absorbing till the pH value of the treated calcium silicate is less than 9; and then sending the treated calcium silicate out of the absorption tower. By using the method, the pH value of the fly ash-coproduced active calcium silicate with high alkalinity can be reduced, and the performance of a calcium silicate filler is improved; and meanwhile, the flue gas can be efficiently purified, the discharge of the flue gas can be reduced, and the sulfur fixation effect is provided.

Description

technical field [0001] The invention relates to a method for reducing the pH value of fly ash co-production calcium silicate filler and simultaneously purifying flue gas, in particular to a method for reducing the pH value of fly ash co-production calcium silicate filler for papermaking and simultaneously purifying flue gas . Background technique [0002] A new type of active silicate processed and extracted from fly ash can be used in the paper industry. However, due to the addition of a large amount of alkali and lime milk in the production process, the product calcium silicate has high alkalinity, which seriously limits its use and promotion in the papermaking field. [0003] On the other hand, the air pollutants produced by coal combustion account for more than 60% of my country's total smoke and dust emissions. Among them, the emissions of smoke from coal-fired power plants and industrial boilers and the emissions of pollutants contained are far greater than other exha...

AI Technical Summary

Problems solved by technology

However, the active calcium silicate produced by this method produces slightly soluble calcium sulfate due to the introduction of sulfate radicals. The introduction of a small amount of calcium sulfate will not have a negative impact on the filler performance of calcium silicate, but this direct The method of pickling with sulfuric acid will lead to too high calcium sulfate content, so that the calcium dissolution rate of the product in the wet end of papermaking is as high as 3.5%, while the dissolution rate of calcium carbonate, a commonly used filler in papermaking, is only 0.29%, which is relatively high. The calcium dissolution rate will have many adverse effects on the papermaking wet end