Method for producing phosphorus pentoxide by phosphorus ore fusion

Abstract

The invention discloses a method for producing phosphorus pentoxide by melting phosphate rock. The phosphate rock and silica are mixed in proportion and sent to a heating furnace for heating and melting. After flowing into the reaction furnace, carbon is added to the molten material and the temperature is controlled to 1200°C. Above, the molten material is reduced in the reduction zone of the reactor to produce a mixed gas of P4 steam and CO and absorb heat. This gas is directly oxidized with the added oxygen in the oxidation zone of the reactor to generate P2O5 and CO2 gases and release heat. The heat is supplied It is necessary to heat the molten material and reduce the heat required for the reduction reaction, control the oxygen addition method in the oxidation zone, maintain the reducing atmosphere on the molten liquid interface of the reactor, and make the reduction and oxidation reaction zones proceed smoothly. The generated P2O5 gas is cooled and purified to produce pentoxide. Phosphorus products. The advantages of the invention are: it simplifies the process, reduces the cost, improves the product quality, has a phosphorus reduction rate of 98%, saves energy and resources, basically eliminates "three wastes", and brings epoch-making changes to the phosphorus chemical industry.

Description

technical field [0001] The invention belongs to the technical field of phosphorus chemical industry and specifically introduces a method for producing phosphorus pentoxide by directly heating and melting medium and low-grade phosphate rocks. Background technique [0002] Phosphorus pentoxide is the acid anhydride of phosphoric acid and is an important intermediate for the production of phosphoric acid. At present, the production process of phosphorus pentoxide in the world is to oxidize and burn yellow phosphorus in dry air to generate high-temperature phosphorus pentoxide vapor. The vapor is precipitated after cooling to obtain phosphorus pentoxide product. [0003] In industry, phosphorus pentoxide is hydrated to generate phosphoric acid, and phosphorus pentoxide is a synonym for phosphoric acid. In order to understand the technical background of the present invention, it is necessary to introduce the production method of phosphoric acid. [0004] At present, there are th...

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Problems solved by technology

[0006] The production cost of wet-process phosphoric acid is low, but it consumes a lot of sulfuric acid. my country is a country lacking in sulfur resources. It imports a large amount of sulfur from abroad every year. The continuous price increase of sulfur has seriously threatened the survival and development of my country's phosphorus chemical industry and phosphate fertilizer industry. ; At the same time, in the production process of wet-process phosphoric acid, a large amount of phosphogypsum will be produced, occupying land and polluting the environment; secondly, wet-process phosphoric acid production can only use P 2 o 5 >28% of high-grade phosphate rock, my country is a country that is poor in phosphate rock, resulting in a large number of phosphate rock mining abandoning the poor and exploiting the rich, and the mining rate of the mine is less than 30%, which is a serious waste of my country's phosphorus resources. Finally, phosphoric acid is poor in quality and low in concentration. It can only produce fertilizer without purification, and the conversion rate of phosphorus can only reach 90%. Therefore, the application field of wet-process phosphoric acid is mainly concentrated in the fertilizer industry

There are still many defects in this process method, such as: the start-up of the system requires high-temperature molten iron; multiple reactions are completed in the same reactor, which is difficult to operate and control; the high-temperature phosphorus pentoxide gas in the oxidation zone and the melting reduction zone are not obvious The reducing atmosphere isolation zone is easy to cause phosphorus pentoxide back absorption, so that the reduction rate can only be reduced to 90%; the high-speed phosphate rock powder, coal powder and phosphorus pentoxide gas are in countercurrent contact, which makes the phosphorus pentoxide gas carry dust. Seriously affect product quality; the system can only be produced intermittently but cannot achieve continuous operation, and the waste residue has high phosphorus content, which is difficult to use and other defects. This technology is difficult to realize industrialization

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