Sulfuric acid with calcium phosphate

C04-0146. The largest single use of sulfuric acid is for the production of phosphate fertilizers. The acid reacts with calcium phosphate in a 2 1 mole ratio to give calcium sulfate and calcium dihydrogen phosphate. The mixture is crushed and spread on fields, where the salts dissolve in rain water. (Calcium phosphate, commonly found in phosphate rock, is too insoluble to be a direct source of phosphate for plants.) (a) Write a balanced equation for the reaction of sulfuric acid with calcium phosphate, (b) How many kilograms each of sulliiric acid and calcium phosphate are required to produce 50.0 kg of the calcium sulfate-dihydrogen phosphate mixture (c) How many moles of phosphate ion will this mixture provide ... 

Tribasic calcium phosphate occurs naturally as the minerals hydroxylapatite, voelicherite, and whitlockite. Commercially, it is prepared by treating phosphate-containing rock with sulfuric acid. Tribasic calcium phosphate powder is then precipitated by the addition of calcium hydroxide. Tribasic calcium phosphate is alternatively prepared by treating calcium hydroxide from limestone with purified phosphoric acid. It may also be obtained from calcined animal bones.Some tribasic calcium phosphate products may be prepared in coarser, directly compressible forms by granulating the powder using roller compaction or spray drying. 

Instead of using sulfuric or phosphoric acid, nitric acid can be used to treat the phosphate lock to produce calcium nitrate fertilizer. Instead of neutralizing phosphoric acid with calcium which is useless, ammonia can be used to give ammonium phosphate, hence, two fertilizing elements. 

When heated in an electric furnace, B2O3 is reduced hy carhon to form horon carbide, B4C, and reacts with calcium phosphate and ammonia to form horon nitride, BN. It reacts with sulfuric acid to produce a horate derivative, H[B(HS04)4]. It combines with several metal oxides to form mixed oxides when heated above 1,000°C. 

Write balanced chemical equations for each of the following processes (a) Calcium phosphate reacts with sulfuric acid to produce calcium sulfite and phosphoric acid, (b) Calcium phosphate reacts with water contaming dissolved carbon dioxide to produce calcium hydrogen carbonate and calcium hydrogen phosphate. 

Extraction of Nonmetallic Inorganic Compounds. Phosphoric acid is usually formed from phosphate rock by treatment with sulfuric acid, which forms sparingly soluble calcium sulfate from which the phosphoric acid is readily separated. However, in special circumstances it may be necessary to use hydrochloric acid ... 

Wet-process acid is manufactured by the digestion of phosphate rock (calcium phosphate) with sulfuric acid. Depending on availabiHty, other acids such as hydrochloric may be used, but the sulfuric-based processes are by far the most prevalent. Phosphoric acid is separated from the resultant calcium sulfate slurry by filtration. To generate a filterable slurry and to enhance the P2O5 content of the acid, much of the acid filtrate is recycled to the reactor. 

Manufacture Mined phosphate rock is reacted with sulfuric acid. The product phosphoric acid is isolated as a 28-35% solution by filtering off the insoluble calcium sulfate co-product. CasfPOJj + SHzSO 2H3P04 + 3CaS04 phosphate sulfuric gypsum rock acid... 

The product, Ca(H2P04)2, is more soluble than the phosphate. Sulfuric acid is produced in the largest quantity of any compound, with production that approaches 100 billion pounds annually. Approximately two-thirds of this amount is used in the production of fertilizers. The mixture containing calcium dihydrogen phosphate and calcium sulfate (gypsum) is known as superphosphate of lime, and it contains a higher percent of phosphorus than does calcium phosphate. 

Prayon One of the Wet processes for making phosphoric acid by reacting phosphate rock with sulfuric acid. The byproduct is gypsum, calcium sulfate dihydrate. It uses a compartmentalized, multi-section, lined, concrete reactor, with finishing tanks in which the gypsum crystals mature. In 1990 one third of the wet process phosphoric acid made in the Western World was made in this way. The process was developed in 1977 by the Societe de Prayon, Belgium. Variations are known as PH2, PHI 1, and PH12. One variation uses solvent extraction with isopropyl ether and tri-n-butyl phosphate. 

The four samples from each location were (1) nonfiltered, nonstabilized water for alkalinity testing, (2) field-filtered, nonstabilized water for nitrate and chloride testing, (3) field-filtered water stabilized with nitric acid for calcium, magnesium, and sodium testing, and (4) field-filtered water stabilized with sulfuric acid for ammonia and phosphate testing. 

Chemically pure reagents were used. Cadmium was added as its sulfate salt in concentrations of about 50 ppm. Lanthanides were added as nitrates. For the experiments with other metal ions so-called "black acid from a Nissan-H process was used. In this acid a large number of metal ions were present. To achieve calcium sulfate precipitation two solutions, one consisting of calcium phosphate in phosphoric acid and the other of a phosphoric acid/sulfuric acid mixture, were fed simultaneously in the 1 liter MSMPR crystallizer. The power input by the turbine stirrer was 1 kW/m. The solid content was about 10%. Each experiment was conducted for at least 8 residence times to obtain a steady state. During the experiments lic iid and solid samples were taken for analysis by ICP (Inductively Coupled Plasma spectrometry, based on atomic emission) and/or INAA (Instrumental Neutron Activation Analysis). The solid samples were washed with saturated gypsum solution (3x) and with acetone (3x), and subsequently dried at 30 C. The details of the continuous crystallization experiments are given in ref. [5]. 

Low-purity technical grade phosphoric acid for use in fertdizers is produced from phosphate rocks by digestion with concentrated sulfuric acid. The apatite types, primarily consisting of calcium phosphate phosphate rocks, are used ... 

Phosphate fertilizer may also be produced by reacting phosphate rock with phosphoric acid that has been produced from sulfuric acid. Phosphoric acid produced from sulfuric acid is called wet process phosphoric acid. In the production of fertilizer using this method, sulfuric acid reacts with the calcium phosphate, (Ca3(P04)2, in the rock to produce phosphoric acid... 

H3P04) and calcium sulfate (CaS04 2H20, also known as gypsum). The phosphoric acid is then processed with the phosphate rock to produce triple superphosphate fertilizer. Triple superphosphate has three times the concentration of phosphorus as superphosphate. Another fertilizer produced from sulfuric acid is ammonium sulfate, (NH4)2S04. Ammonium sulfate is produced by reacting ammonia and sulfuric acid. 

Two major methods are utilized for the production of phosphoric acid from phosphate rock. The wet process involves the reaction of phosphate rock with sulfuric acid to produce phosphoric acid and insoluble calcium sulfates. Many of the impurities present in the phosphate rock are. also solubilized and retained in the acid so produced. While they are of no serious disadvantage when the acid is to be used for fertilizer manufacture, their presence makes the product unsuitable for the preparation of phosphatic chemicals. 

The utilization of tricalcium phosphate therefore requires its conversion into a soluble salt. This is accomplished by treating the normal phosphate with dilute sulfuric acid (lead-chamber acid), thereby producing the soluble primary calcium phosphate ... 

The majority of the phosphoric acid is made by the wet process, which involves reaction of calcium phosphate or the mixed calcium fluoride-calcium phosphate ores with sulfuric acid. 

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