Method for producing phosphorus pentoxide by phosphorus ore fusion

Abstract

The invention discloses a method for producing phosphorus pentoxide by melting phosphate rock. Phosphate rock and silica are mixed in proportion, sent to a heating furnace for heating and melting, and after flowing into the reaction furnace, carbon is added to the molten material, and the temperature is controlled to 1200°C. As mentioned above, the molten material is reduced in the reduction zone of the reaction furnace to produce a mixed gas of P4 steam and CO and absorb heat. The gas is directly oxidized with the added oxygen in the oxidation zone of the reaction furnace to generate P2O5 and CO2 gas and release heat. The heat supply Heating the molten material and reducing the heat required by the reduction reaction, controlling the way of adding oxygen to the oxidation zone, maintaining the reducing atmosphere on the molten liquid interface of the reaction furnace, so that the reduction and oxidation reactions can be carried out smoothly, and the generated P2O5 gas is cooled and purified to obtain dioxide Phosphorus products. The invention has the advantages of simplifying the process, reducing the cost, improving the product quality, reducing the phosphorus to 98%, saving energy and resources, basically eliminating "three wastes", and bringing 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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