Method for preparing phosphoric acid with high density by microwave heating of fertilizer grade phosphoric acid

Abstract

The invention discloses a method for preparing phosphoric acid with high density by microwave heating of fertilizer grade phosphoric acid, the method comprises the following steps: taking the fertilizer grade phosphoric acid produced by a wet method as a raw material acid, then pretreating and removing arsenic, removing fluorine and filtering, then performing microwave heating and concentrating to obtain the phosphoric acid with high density. The obtained phosphoric pentoxide possesses the characteristics of high content, small corrosivity on the equipment and material and short concentration time; and the method of the invention has the advantages of simple process, easy industrialization, low cost and less investment, the storage cost and transportation cost of phosphoric acid can be simultaneously reduced, thereby the requirements of different users can be satisfied, and the method of the invention is a production technology with good economic benefit.

Description

technical field [0001] The invention relates to phosphoric acid, in particular to a method for preparing high-concentration phosphoric acid by using fertilizer-grade phosphoric acid produced by a wet method as a raw material acid and concentrating it through a special process. technical background [0002] Phosphoric acid is a very important intermediate product in the phosphorus chemical industry, widely used in fertilizer, food, water treatment, paint, pigment, washing, flame retardant, medicine, electronics and other industries. According to the content of impurities in phosphoric acid, phosphoric acid is generally divided into fertilizer grade, industrial grade, food grade and electronic grade, etc., and the mass percentage concentration of phosphoric acid is 60-85% (in terms of H 3 PO 4 %count). [0003] At present, there are generally two methods for producing phosphoric acid in industry, namely thermal phosphoric acid and wet phosphoric acid. Thermal phosphoric a...

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Problems solved by technology

Thermal phosphoric acid products have high purity and low impurity content, but high production costs and high energy consumption. Compared with thermal phosphoric acid, wet-process phosphoric acid has the advantages of low energy consumption and low production costs, but the product has high impurity content and generally needs to be removed , purification and other processes are applied in industry

[0004] Existing patent reports on the preparation of high-concentration phosphoric acid are less, and generally adopt thermal phosphoric acid with low impurity content as raw material, dehydrate and concentrate at a certain temperature The phosphoric acid prepared by this method not only has high phosphoric acid content and low impurity content, but also has good color and product fluidity, but the cost of raw materials used is high and there is no economic advantage; there are also industrial grade or food grade phosphoric acid produced by wet method Phosphoric acid is prepared by dehydration and concentration of raw materials, but the process steps are complicated and cumbersome; there is also an absorption method, which burns yellow phosphorus to obtain phosphorus pentoxide, and cools and absorbs it with pre-cooled phosphoric acid to produce polyphosphoric acid and high-concentration phosphoric acid Product, this method is similar to the process of producing thermal phosphoric acid in industry, although the product quality is good and the impurity content is low, but the production cost is high, resulting in high product price

But so far, there is no report on the production of high-concentration phosphoric acid by microwave heating concentrated phosphoric acid, and there is no related patent

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