CN1232005A

CN1232005A - Process for preparing phosphate fertilizer and soda by circulation of ammonium chloride

Info

Publication number: CN1232005A
Application number: CN 99114752
Authority: CN
Inventors: 黄孝农; 张世光
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-30
Filing date: 1999-03-30
Publication date: 1999-10-20

Abstract

An ammonium chloride cycle process for preparing P fertilizer and sodium carbonate includes crushing 16-20% (P content) low-grade phosphorus ore (1 pts. wt.) and CaO (0.1-0.5 pts.wt.), mixing with NH4Cl (0.2-1 pts.wt.), calcining at 750-950 deg.C for 5-40 min to obtain P fertilizer, and reaction of NH3 gas and CO2 generated on calcining with NaCl to obtain sodium carbonate and the by-product NH4Cl which can be cyclically used. Its advantage is low cost.

Description

Process for preparing phosphate fertilizer and soda by circulating ammonium chloride method

The invention relates to a process for preparing a phosphate fertilizer and soda ash by an ammonium chloride circulation method, which relates to the preparation of the phosphate fertilizer and the soda ash and belongs to the field of inorganic chemical industry.

The existing phosphate fertilizer production process is a thermal method phosphate process, such as the production of calcium magnesium phosphate fertilizer, defluorinated phosphate fertilizer, thermal method phosphate and the like, all of which need to use Ca-containing₅(PO₄)₃F and is reduced to the total phosphorus content (Tp)₂o₅) High-grade and medium-grade phosphorus ore not less than 25%, and can be prepared at high temperature not less than 1350 deg.C, and has total phosphorus content (Tp)₂o₅) The low-grade phosphate ore with the concentration less than or equal to 20 percent can not be used at all and becomes mine waste residue.

The existing soda production process basically adopts two methods, namely an ammonia-soda method (Suweier method) and a combined-soda method (Hough soda method) at home and abroad. Because the utilization rate of the ammonia-soda process to the salt is not high, generally 75%, and the chloride ions in the salt are not utilized at all, a large amount of chloride in the production process is dischargedThe calcium chloride waste liquid of the salt is basically not adopted in China. The combined alkali method can be used for producing NH although the utilization rate of the salt is high₄Cl, basically has no three-waste discharge, but has the disadvantage that a synthetic ammonia plant with the corresponding size is required to be matched with the Cl to provide the required ammonia (NH)₃)。

The invention aims to provide a process for producing phosphate fertilizer and soda ash by using low-grade phosphate ore as a raw material, and the production cost is reduced.

The purpose of the invention is realized by the following technical scheme:

1 part of low-grade phosphate ore with 16-20% of total phosphorus content and 0.1-0.5 part of CaO are crushed and then mixed with 0.2-1 part of NH₄Mixing Cl, adding into a heating device, calcining for 5-40 minutes at 750-950 ℃, wherein the prepared clinker is citrate soluble phosphorus fertilizer product, and NH is generated during calcining₃Gas, CO₂Can react with NaCl to produce sodium carbonate, the by-product NH₄The Cl can be returned to react with the phosphate ore and CaO for recycling.

In the scheme, the calcined clinker can be washed and filtered, the filter cake is dried to obtain a citrate soluble phosphate fertilizer product, and the filtrate is decocted to obtain anhydrous CaCl₂。

In the scheme, the preparation of the calcined soda is the prior art, namely NH₃、CO₂NH is prepared by water absorption in an absorber₄HCO₃Filtering the slurry to obtain NH₄HCO₃Filter cake, per NH portion₄HCO₃With 0.7-1 part of refined salt (NaCl) and 4-6 parts of NH₄Reacting the Cl clear mother liquor or water at 30-40 ℃ for 1-3 hours to obtain NaHCO₃Precipitation and NH₄Filtering and separating Cl solution to obtain filter cake of NaHCO₃Calcining at 500-800 ℃ for 0.5-2 hours to obtain a soda product; CO decomposed in calcination₂Can be returned to the absorber to react with NH₃Carrying out reaction; NH contained in the filtrate₄The Cl is cooled and crystallized to prepare NH₄Cl slurry is filtered to obtain NH₄Cl crystals which can be returned to react with low-grade phosphate ore and CaO for filteringThe liquid is settled to obtain NH₄The clear mother liquor of Cl can be returned to be used as NH₄HCO₃Medium for reaction with NaCl.

In the technical scheme, Ca in the phosphate ore₅(PO₄)₃Decomposition of F, based mainly on CaCl₂Partial decomposition at high temperature (inorganic salt technology, ME Borden, etc., published by chemical industry Press in 9 months 1982; pure chemical reagents, Carerweijin, advanced education Press in 1 month 1957) to subject the batch to acid hydrolysis:

……(1)

……(2)

……(3)

phosphoric acid reacts with phosphorite to prepare calcium salt of phosphoric acid, and calcium metaphosphate, calcium pyrophosphate, calcium phosphate and the like which can be dissolved in citric acid solution (citrate solution) can be finally generated at high temperature.

NH₄Cl can sublime at higher temperatures to form NH₄The fumes of fine Cl particles, in the presence of water, may also partially react: … … (4), and acid hydrolyzing the phosphate ore.

SiO contained in phosphorite during calcination₂Reacts with CaO to generate CaSiO₃To form amorphous material, thereby making the product citrate soluble.

NH of phosphate ore₄Cl treatment to obtain citrate soluble phosphate fertilizer should be the comprehensive result of the above reaction or more chemical reactions.

The production of soda ash is based on the following reaction:

………(5)

………(6)

comparedwith the process for preparing the calcined soda by the combined soda process, the invention has the advantages thatBesides the same advantages, the method saves a matched synthetic ammonia plant, reduces investment, equipment and personnel, thereby reducing product cost, and can co-produce phosphate fertilizer and byproduct CaCl₂。

Compared with available phosphate fertilizer producing process, the present invention can adopt low grade phosphate rock with total phosphorus content not lower than 17%, and the phosphate rock is discarded as waste in domestic mine. In addition, the quality of the phosphate fertilizer prepared by the method is higher than that of a product prepared by high-grade and medium-grade phosphate ores. Phosphorus ore containing 17-22.25% of total phosphorus is adopted to prepare phosphorus containing 13.70-17.75% of available phosphorus, and the phosphorus is processed at a moderate temperature.

FIG. I is a schematic view of the process of the present invention.

The following is an example of the invention in which the phosphorus ore has a total phosphorus content (Tp)₂o₅) 16.95 to 25.38 percent of the total weight of the calcium oxide, the calcium oxide is the basic slag of the converter in the steel plant, the CaO content is about 95 percent, and the purity of the ammonium chloride is more than or equal to 98.5 percent.

Example one

Phosphorus ore powder (Tp)₂o₅= 25.38%), NH 20 parts₄Cl10 parts and quicklime powder 5.6 parts, evenly mixed and calcined at 720 ℃ for 35 minutes to obtain citrate soluble product with the total phosphorus content Tp₂o₅= 19.01%, available phosphorus Cp₂o₅= 8.83%, conversion C/T = 46.45%, yield 26.7 parts.

Example two

In the same manner as in the first example except that the calcination temperature was 770 ℃ and the calcination time was 30 minutes, Tp in the product₂o₅=19.52％,Cp₂o₅= 13.14%, C/T = 63.73%, yield 26 parts.

EXAMPLE III

In the same manner as in the first example, Tp was added to the product except that the calcination temperature was 800 ℃ and the calcination time was 15 minutes₂o₅=19.37％,Cp₂o₅= 15.56%, C/T = 80.33%, yield 26.2 parts.

Example four

In the same manner as in the first example, Tp in the product was added to the product except that the calcination temperature was 870 ℃ and the calcination time was 10 minutes₂o₅=18.94％,Cp₂o₅= 15.46%, C/T = 81.63%, yield 26.8 parts.

EXAMPLE five

In the same manner as in the first example, Tp was added to the product except that the calcination temperature was 920 ℃ and the calcination time was 5 minutes₂o₅=19.67％,Cp₂o₅= 14.77%, C/T = 73.77%, yield 25.8 parts.

EXAMPLE six

Removing NH₄The rest of the example I is the same as that of Tp in the product except that the dosage of Cl is 6 parts, the dosage of quicklime powder is 3.5 parts, the calcining temperature is 870 ℃, and the calcining time is 20 minutes₂o₅=21.88％,Cp₂o₅= 6.9%, C/T = 31.54%, yield 23.2 parts.

EXAMPLE seven

Removing NH₄The dosage of Cl is 16parts, the dosage of quicklime powder is 8 parts, the rest is the same as that of the sixth embodiment, Tp in the product₂o₅=16.92％,Cp₂o₅= 16.29%, C/T = 96.22%, yield 30 parts.

Example eight

The process is similar to the seventh embodiment except that the calcined clinker is washed with water, filtered and the filter cake is dried to obtain the citrate soluble phosphorus fertilizer product, wherein Tp is Tp₂o₅=23.39％,Cp₂o₅= 22.3%, C/T = 95.4%, yield 21.7 parts.

Example nine

Total phosphorus content TP of phosphorus removal ore powder₂o₅In addition to 16.95%, the TP in the product of example one₂P₅=16.9％,Cp₂o₅=14.9％,C/T=88.02％。

Example ten

NH generated in example two₃And CO₂In the absorber, NH is generated through multi-stage water absorption₄HCO₃Slurry is filtered, and filter cake is NH₄HCO₃The filtrate returns toCan be reused as absorption liquid. Per part of NH₄HCO₃Adding 0.7 part of NaCl and 4 parts of NH₄Mother solution of Cl is reacted for 3 hours at 30 ℃ to obtain NaHCO₃Precipitation and NH₄Filtering and separating Cl solution to obtain filter cake of NaHCO₃Calcining at 560 deg.C for 2 hr to obtain soda ash product. CO decomposed in calcination₂Returning to the absorber to react with NH₃And (4) reacting. NH contained in the filtrate₄The Cl is cooled and crystallized to prepare NH₄Cl slurry is filtered to obtain NH₄And the Cl crystals are returned to the second embodiment to react with the low-grade phosphorite and CaO. Settling the filtrate to obtain NH₄Mother liquor of Cl, returned as NH₄HCO₃Medium for reaction with NaCl. The sedimentation liquid returns to be filtered.

EXAMPLE eleven

NH generated in example III₃And CO₂NH generated by multi-stage water absorption in an absorber₄HCO₃Mixing each part with 1 part of NaCl and 6 parts of NH₄The mother solution of Cl is reacted for 1 hour at 40 ℃ to prepare NaHCO₃Calcining at 800 deg.C for 30 min to obtain soda ash product. The other steps are the same as those of the tenth embodiment.

Claims

1. A process for preparing phosphate fertilizer and soda by ammonium chloride circulation method is characterized in that 1 part of low-grade phosphate ore with 16-20% of total phosphorus content and 0.1-0.5 part of CaO are crushed and then mixed with 0.2-1 part of NH₄Mixing Cl, adding into a heating device, calcining for 5-40 minutes at 750-950 ℃, wherein the prepared clinker is citrate soluble phosphorus fertilizer product, and NH is generated during calcining₃Gas, CO₂Can react with NaCl to produce sodium carbonate, the by-product NH₄The Cl can be returned to react with the phosphate ore and CaO for recycling.

2. The process of claim 1, wherein the calcined clinker is washed with water, filtered, the filter cake is dried to obtain citrate soluble phosphate fertilizer, the filtrate is decocted to obtain anhydrous CaCl₂。

3. The process for preparing P fertilizer and soda ash by circulating ammonium chloride as claimed in claim 1, wherein the preparation of soda ash is prior art,i.e. NH₃、CO₂NH is prepared by water absorption in an absorber₄HCO₃Filtering the slurry to obtain NH₄HCO₃Filter cake, per NH portion₄HCO₃With 0.7-1 part of refined salt (NaCl) and 4-6 parts of NH₄Reacting the Cl clear mother liquor or water at 30-40 ℃ for 1-3 hours to obtain NaHCO₃Precipitation and NH₄Filtering and separating Cl solution to obtain filter cake of NaHCO₃Calcining at 500-800 ℃ for 0.5-2 hours to obtain a soda product; CO decomposed in calcination₂Can be returned to the absorber to react with NH₃Carrying out reaction; NH contained in the filtrate₄The Cl is cooled and crystallized to prepare NH₄Cl slurry is filtered to obtain NH₄Cl crystal can be returned to react with low-grade phosphate ore and CaO, and NH is obtained by settling filtrate₄The clear mother liquor of Cl can be returned to be used as NH₄HCO₃Medium for reaction with NaCl.