Production method for co-producing cement and sulfuric acid by using gypsum

Abstract

The invention discloses a production method for co-producing cement and sulfuric acid by using gypsum. The method comprises the following steps: carrying out hierarchical heating on a raw material A containing gypsum and coke in a hierarchical suspending pre-heater, heating and carrying out reducing decomposition on the heated gypsum raw material A in a reducing decomposition fixed bed with pulverized coal combustion, transmitting a reducing decomposition gas C generated after the reducing decomposition into the hierarchical suspending pre-heater, carrying out heat exchanging with the gypsum cement raw material A, purifying for sulfuric acid production; transmitting a material after the reducing decomposition into a cement clinker sintering fixed bed, carrying out heating sintering with pulverized coal combustion, so as to obtain a cement clinker B. Compared with the prior art, the production method for co-producing cement and sulfuric acid by using gypsum disclosed by the invention has the advantages that the dosages of reducing coal and sintering coal are reduced, the sulfur dioxide concentration in the reducing decomposition gas and the quality of a cement clinker are increased, the purposes of saving energy source, reducing production cost, enhancing production capacity, reducing investment and increasing economic benefit of a producer are realized, and the environment-protection problem of phosphor-gypsum stacking treatment is solved.

Description

technical field [0001] The invention relates to a production method for co-production of sulfuric acid with cement produced from gypsum, in particular to a production method for co-production of sulfuric acid with phosphogypsum for production of cement. Background technique [0002] The production of phosphogypsum is produced by the precipitation and crystallization of phosphate rock and sulfuric acid during the production of phosphoric acid by wet process phosphorus chemical industry. The chemical reaction principle is as follows: [0003] Ca 5 F(PO 4 ) 5 +H 2 SO 4 +10H 2 o [0004] → 3H 3 PO 4 +5CaSO 4 2H 2 O↓+HF↑ [0005] Production of one ton of phosphoric acid (P 2 o 5 %) to produce 5-6 tons of solid phosphogypsum. In 2012, my country's wet-process phosphoric acid production was about 15 million tons (P 2 o 5 %), more than 90 million tons of solid phosphogypsum were produced. A large amount of phosphogypsum discharge requires a large amount of money an...

AI Technical Summary

Problems solved by technology

Compared with natural gypsum or desulfurized gypsum, phosphogypsum has four major disadvantages: First, in the production of phosphorus chemical industry, in order to achieve the best utilization rate of phosphate rock, it is easier to filter and wash, and the phosphogypsum crystal particles need to be coarse, resulting in the use of phosphogypsum. When used in gypsum products, the specific surface area is low, and the activity is not good; the second is that some trace soluble components and residual phosphorus brought along with the liquid holding capacity of phosphogypsum, after entering the gypsum products, due to changes in the humidity in the air, salt frost and Mildew; the third is that due to the different mineral sources in phosphogypsum, in addition to the constant calcium, sulfur, and silicon components contained in it, the content of trace and ultra-trace impurities is different, resulting in differences in the morphology, specific surface, and reactivity of the produced phosphogypsum There are endless changes; the fourth is the limitation of economic value brought about by the inherent economic value of gypsum products and the transportation costs of gypsum products

However, this method also has many deficiencies: one is that the introduced auxiliary agent CaCl 2 , due to the decomposition of chlorides, chlorides must be excluded from the tail gas, which is very unfavorable to the production of sulfuric acid, and will cause chlorine-based corrosion to sulfuric acid equipment; second, when the chlorides will decompose with the organic matter in the coal powder at high temperature, polychlorinated diphenyls will be produced or polychlorinated diphenylfurans, which are toxic to the environment, such as Dioxins (Dioxins); the third is the introduction of Na 2 SO 4 The sodium ions in the cement directly affect the product quality of cement due to its strong water solubility; fourth, it is also impossible to fundamentally solve the chemical reaction kinetics core of the gas phase atmosphere required for the reduction and decomposition of gypsum and the firing of cement clinker, and the balance between reduction and decomposition and oxidation firing Fifth, the product prices of these additives are much higher than the unit price of cement and sulfuric acid, which increases the cost of raw materials

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