A system and method for preparing phosphoric acid and silicon-calcium-potassium-magnesium fertilizer from phosphate rock

Abstract

The invention provides a system and a method for preparing phosphoric acid and a calcium silicon potassic-magnesian fertilizer from phosphorus ores. The system comprises an acid leaching unit, a solid-liquid separation device, an extraction device, a pelletizing unit, a baking device, a hydrochloric acid absorption unit and a tail gas purification device, wherein the acid leaching unit is respectively connected with the solid-liquid separation device and the hydrochloric acid absorption unit; a liquid outlet of the solid-liquid separation device is connected with the extraction device; a raffinate outlet of the extraction device and a solid outlet of the solid-liquid separation device are both connected with the pelletizing unit; the pelletizing unit, the baking device and the hydrochloricacid absorption unit are sequentially connected; a liquid outlet of the hydrochloric acid absorption unit is connected with the acid leaching unit. According to the invention, hydrochloric acid is utilized to treat phosphorus ore powder to produce the phosphoric acid and the calcium silicon potassic-magnesian fertilizer; after being purified, the obtained phosphoric acid has purity of 85% or more; hydrochloric acid can be regenerated for recycling; according to the invention, no solid-liquid wastes are generated, the method is a wet phosphoric acid clean production process, and a new approachis provided for comprehensive utilization of the phosphorus ores.

Description

technical field [0001] The invention belongs to the technical field of phosphorus chemical production and relates to a system and method for preparing phosphoric acid and silicon calcium potassium magnesium fertilizer from phosphate rock. Background technique [0002] The inorganic phosphorus chemical industry includes the production of inorganic phosphorus compounds such as phosphate, and is one of the important chemical industry series products. At present, my country has established a relatively complete phosphorus chemical production system, which can basically meet the needs of economic growth and production level improvement, and has exported a large number of products, becoming the world's largest producer, consumer and exporter of phosphorus chemicals. [0003] However, there are still serious environmental problems in the production of phosphorus chemical industry. According to statistics, every ton of production contains 100% P 2 o 5 phosphoric acid will produce ...

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Problems solved by technology

CN 101456545 A discloses a method for producing double superphosphate and co-producing calcium chloride with medium and low-grade phosphate rock. The method includes two parts, one of which is acid hydrolysis of phosphate rock powder 1 with hydrochloric acid and partial extraction of acid hydrolysis solution 1. Extract organic reverse extraction to prepare phosphoric acid, react the raffinate aqueous phase with milk of lime to obtain calcium hydrogen phosphate and calcium chloride; Calcium superphosphate; although the above method can obtain double superphosphate and calcium chloride, the preparation process is relatively complicated, the resulting product is not pure enough, and the utilization rate of hydrochloric acid is low

CN 101774556A discloses a method for preparing industrial-grade and food-grade phosphoric acid by decomposing medium and low-grade phosphate rock with hydrochloric acid. The method sequentially includes hydrochloric acid acid-decomposing phosphate rock powder, extracting and removing iron, preparing dilute phosphoric acid, preparing industrial-grade phosphoric acid and preparing food-grade phosphoric acid. Phosphoric acid, wherein, the steps of preparing industrial-grade phosphoric acid from dilute phosphoric acid include concentration, de-arsenic and heavy metal removal, decolorization, filtration, deep decolorization and concentration adjustment, etc. The preparation of food-grade phosphoric acid also includes the step of deep defluorination; this method can obtain high-purity Phosphoric acid, but the preparation process of this method is relatively complicated, there are still harmful solid wastes, and the phosphate rock resources cannot be fully utilized

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