Double-calcination process of sulfuric acid and rare earth concentrate rotary kiln calcination device

Abstract

The invention provides a sulfuric acid and rare earth concentrate rotary kiln calcination device. The device is characterized in that burnt waste gases of a high-temperature calcining kiln of a calcining kiln burning system are emitted to a low-temperature calcining kiln via a flue gas emission pipeline and the waste heat of the waste gases is reutilized; burnt waste gases of the low-temperature calcining kiln are emitted to a scattering dryer and the waste heat of the waste gases is reutilized; waste gases in the scattering dryer are emitted after undergoing gas-solid separation; waste gases at the inlet of the high-temperature calcining kiln are emitted after undergoing gas-solid separation; sulfuric acid and rare earth concentrate calcining materials of a calcining kiln system are calcined in the low-temperature calcining kiln and enter the inlet end of the high-temperature calcining kiln via the outlet end; and the calcining materials are calcined in the high-temperature calcining kiln and are discharged into a dissolving tank via a discharge pipe on one side of a cooling machine. The device has the following beneficial effects that the rare earth concentrate is subjected to full calcination at low temperature and at high temperature respectively, thus improving decomposition of the rare earth concentrate; the waste heat of the calcining kilns is recycled; the sulfuric acids in the recovered waste gases are used for production; the waste residues are reduced and the air is purified; and the device has strong process continuity, high degree of automation and low labor intensity and improves production.

Description

technical field [0001] The invention relates to a rare earth concentrate roasted by a rotary kiln, in particular to a secondary roasting process of a rotary kiln roasting device for a rare earth sulfate concentrate. Background technique [0002] Since the 1970s, my country began to develop the use of concentrated sulfuric acid roasting method to smelt Baotou mixed rare earth concentrates, and successively developed the first, second and third generation sulfuric acid methods, among which concentrated sulfuric acid high-temperature intensive roasting method (third-generation acid method) It has been put into use since the 1980s and has become the leading industrial production technology for processing Baotou rare earth concentrates. At present, 90% of Baotou rare earth concentrates are processed by concentrated sulfuric acid high-temperature intensified roasting. [0003] Concentrated sulfuric acid high temperature intensified roasting method (third-generation acid method) mai...

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Problems solved by technology

[0004] The main defects of this process are: (1) thorium exists in the waste residue in the form of pyrophosphate, which cannot be recycled, causing the waste of thorium resources to exceed the standard; (2) a large amount of waste gas is produced at the kiln tail, and the waste gas contains HF, SO 2 , SO 3 , sulfuric acid mist and other harmful components, resulting in difficult waste gas treatment technology, complex process, high investment and operating costs, in view of the above reasons, it is necessary to improve the device and roasting process of rare earth concentrate roasting kiln

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