Rotary kiln for reducing phosphate rock in kiln phosphoric acid process and method for solving kiln tail ring formation in kiln phosphoric acid process

Abstract

Disclosed is a rotary kiln for reducing phosphate ore in a kiln process for the production of phosphoric acid, comprising a kiln body, a kiln head box, a kiln tail box and a driving device for driving the rotation of the kiln body, wherein a fuel burner is provided at the kiln head, a feeding pipe and an outlet flue connected to an external hydration tower are provided at the kiln tail box, the upper part of the kiln body is provided with no air pipe, the outlet flue is provided in the radius range of the kiln body with the axis of the rotary kiln as a centre, and the smoke conveying direction in the outlet flue is substantially parallel to the axis direction of the rotary kiln or has an included angle of less than 45° thereto. When using the rotary kiln of the present invention for the kiln process for the production of phosphoric acid, the raw materials enter from the kiln tail box, the fuel burner is ignited for heating, the phosphate ore raw material is reduced under a high-temperature condition to produce a smoke exiting the kiln, and in the present invention, the smoke exiting the kiln is allowed to enter the outlet flue without large shifting, thereby preventing the centrifugal physical sedimentation at the kiln tail such that the metaphosphoric acid in the kiln smoke directly enters the hydration tower along with the kiln smoke. The present invention can effectively mitigate the phenomenon of ring forming in the kiln tail of the rotary kiln.

Description

technical field [0001] The invention relates to a reaction device for reducing phosphate rock, in particular to a rotary kiln for reducing phosphate rock. 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 water, and are easily washed away by rain after natural stacking. It causes serious pollution to the environment...

AI Technical Summary

Problems solved by technology

[0016] In our long-term industrial application practice of kiln-based phosphoric acid process, the ring formation at the end of the rotary kiln has always been a major technical problem for those skilled in the art. Due to the ring formation at the end of the rotary kiln, the process raw material balls cannot be added into the rotary kiln. At the same time, it also blocks the normal movement of the airflow in the rotary kiln. Practice has proved that if the problem of ring formation at the kiln tail is not solved, the process cycle will be shortened, resulting in a decrease in process efficiency and a significant increase in process cost. s failure

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