Raw material pretreatment method and raw material pretreatment process system suitable for kiln method phosphoric acid technology

Abstract

Disclosed is a raw material pre-treatment process system suitable for a kiln process for the production of phosphoric acid, comprising carbonaceous reductant, phosphate ore and silica pre-treatment systems independent from each other, wherein the outlet of each pre-treatment system is connected to a core material mixing device via a conveying device, the outlets of the carbonaceous reductant and silica pre-treatment systems are connected to a shell material mixing device via an additional conveying device, and each pre-treatment system mainly consists of a single-stage crushing device, an intermediate bin, an ore grinding device, a storage bin and a formulating device. Also disclosed is a raw material pre-treatment process suitable for a kiln process for the production of phosphoric acid, i.e. pre-treating the carbonaceous reductant, phosphate ore and silica with the respective pre-treatment systems, correspondingly, then sending same into the core material mixing device for pelletising, and sending the pre-treated carbonaceous reductant and silica to the shell material mixing device for mixing. The present invention has the significant advantages of reasonable structural optimisation, low cost, small energy consumption and ensuring the stable operation of the kiln process for the production of phosphoric acid etc.

Description

technical field [0001] The invention relates to a raw material pretreatment method and equipment in a phosphoric acid production process, in particular to a raw material pretreatment method and a pretreatment process system in a kiln phosphoric acid process (KPA). Background technique [0002] At present, there are two main methods for the industrial production of phosphoric acid in the world. (1) Phosphoric acid production by wet method: that is, using sulfuric acid to decompose phosphate rock to obtain dilute phosphoric acid and CaSO 4 ·nH 2 O is the main solid waste (referred to as phosphogypsum), and dilute phosphoric acid is concentrated to obtain wet-process phosphoric acid containing about 54% phosphoric acid. The main disadvantages of this process are: first, it consumes a large amount of sulfuric acid; second, the waste residue phosphogypsum cannot be effectively utilized, and the entrained sulfuric acid, phosphoric acid and soluble fluoride are all soluble in wat...

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Problems solved by technology

The main disadvantages of this process are: first, it consumes a large amount of sulfuric acid; second, the waste residue phosphogypsum cannot be effectively utilized, and the entrained sulfuric acid, phosphoric acid and soluble fluoride are all soluble in water, and are easily washed away by rain after natural stacking. It causes serious pollution to the environment; thirdly, the impurity content of phosphoric acid in the product is relatively high, and it is generally only used for the production of fertilizer; fourthly, in order to ensure the economy of the product, high-grade phosphate rock must be used

The main disadvantages of thermal phosphoric acid production: one is to consume a lot of electric energy; the other is to separate the P 4 The gas also contains a large amount of fluoride (SiF 4 and HF present) and a small amount of unprecipitated gas P 4 , which will cause serious pollution to the atmospheric environment; third, the gas containing a large amount of CO is directly burned and emptied, which is a great waste of energy; fourth, in order to ensure the economy of production, it is also necessary to use high-grade phosphate rock

[0005] However, our research shows that the above-mentioned kiln phosphoric acid process is difficult to realize in large-scale industrial application and practice, and its main defects are:

First of all, the pretreatment equipment selected in the raw material pretreatment stage and the pretreatment process system combined therefrom are not reasonable and scientific enough, which leads to relatively high process costs and energy consumption in the raw material pretreatment stage; more prominent technical problems Yes, the composition of the raw materials sent to the rotary kiln fluctuates greatly, and the mixing of the raw materials is not uniform enough, which leads to CaO / SiO in the composite pellets 2 The molar ratio fluctuates greatly, which further aggravates the problem of high-temperature ring formation of the powder in the rotary kiln, further increasing the risk of process failure

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