Method for preparing light calcium carbonate and co-producing ammonium sulfate from ardealite

Abstract

The invention discloses a method for preparing light calcium carbonate and co-producing ammonium sulfate from ardealite. The method comprises the following steps of: step 100, converting ardealite into a soluble calcium ion solution through an ammonia-containing phase transfer agent; step 200, converting calcium ions in the soluble calcium ion solution into calcium carbonate precipitate through precipitation reaction; step 300, automatically removing the generated calcium carbonate precipitate in the precipitation reaction process; step 400, repeating the step 300 until no calcium carbonate precipitate is generated, and concentrating and crystallizing the residual liquid to obtain ammonium sulfate. According to the invention, generated calcium carbonate is continuously removed in the precipitation reaction process, on one hand, the removed calcium carbonate precipitate reduces the stirring difficulty of the whole reaction liquid and improves the collision probability of reactants so as to increase the conversion rate of calcium ions, and on the other hand, in terms of reaction balance, products are continuously removed, the whole reaction balance is promoted to move towards the direction of products of the precipitation reaction, so that the yield of calcium carbonate is further improved.

Description

technical field [0001] The invention relates to the technical field of comprehensive utilization of industrial by-product gypsum, in particular to a method for preparing light calcium carbonate and co-producing ammonium sulfate from phosphogypsum. Background technique [0002] Phosphogypsum is the waste slag discharged from wet-process phosphoric acid production enterprises, producing 1 ton of phosphoric acid (with 100% P 2 o 5 Total) produces 4.8-5.0 tons of phosphogypsum. At present, the world's output of phosphogypsum has exceeded 280 million tons, while my country's output has exceeded 50 million tons, and the comprehensive utilization rate is less than 30%. Phosphogypsum is mainly calcium sulfate dihydrate, which contains a small amount of harmful impurities such as phosphorus, fluorine, iron, aluminum, magnesium, silicon, etc., and has a pH value of 4-5. Phosphogypsum is mainly used as cement retarder, gypsum brick and other building materials, but the characteristi...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for preparing light calcium carbonate and co-producing ammonium sulfate from phosphogypsum, so as to solve the technical problem in the prior art that the yield is not high because the product calcium carbonate cannot be transferred in time

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