DE1018850B - Process for decalcifying phosphates containing lime, clay and iron - Google Patents

Description

Process for decalcifying lime, clay and iron containing Phosphates It is known, alumina iron phosphates na.ßalka, -lisch or pyro: genalka, lis.ch to unlock, with trialkalipho, spha.t, alkali, luminiat and / or iron oxyhydrate develop. Much of the naturally occurring. Contains clay, earth iron phosphates but varying amounts of calcium phosphate, sometimes even in molecular form. This Phosphate bound to calcium goes into the insoluble residue during alkaline digestion and cannot be used as a full-fledged fertilizer even without further treatment. It is also known, calcium phosphates: which have a more or less high content to have @ alumina and iron, by treating with subordinate. Amounts of mineral acid, z. B. sulfuric acid or hydrochloric acid, to be enriched in their calcium phosphate content by thereby considerable amounts of clay b: zw. this removes aluminum oxide.

It was now; found that the calcium was also removed from the rock phosphate in an acidic way and so the P.0 contained in the raw pho: sp: has . and the clay can be obtained practically completely by wet alkaline methods.

In the process according to the invention, ground rock phosphate is added with an excess, preferably two to five times the amount of acid on the Ca 0 contained in the rock phosphate. Such inorganic acids can be: Acids are used that form water-soluble salts with the cailcium. With application of the acid excess mentioned: the lime becomes 90 to. 99% from the alumina iron phosphate drained.

The mix of. Rock phosphate and acid will get to temperatures above 110 °, preferably 1.50 to 300 °, heated. The excess is used Acid recovered and the reaction product brought to dryness. It is appropriate Heating temperatures at which the calcium salts decompose should not be exceeded. All formed intermediately, eten. Salts of the applied acid decompose, under Reduction of the corresponding phosphates, only the calcium. lies as salt the acid used. The calcium salt formed is then mixed with water almost quantitatively leached and can then be obtained by crystallization. will.

The still moist residue becomes moderately alkaline in a manner known per se. open-minded and processed on Trialkaliphosp: has, clay and / or irono: xydhydra, t, with all components obtained quantitatively. will.

Example 1 100 kg calcined. Alumina-claret phosphate of the following composition: P205 ......................... 34.7% A1203 . . . . . . . . . . . . . . . . . . . . . . . . 36.811 / 0 Ca0. . . . . . . . . . . . . . . . . . . . . . . . . . 11.6% Fairy 03. . . . . . . . . . . . . . . . . . . . . . . . 11.40 / a F ................................ 0.640 / 0 S i 02. . . . . . . . . . . . . . . . . . . . . . . . . 3, 9 0/0 Loss on ignition .................... 1.2% 190 kg about 35% hydrochloric acid is added in a closed container, mixed well and moistened. The goods heat up through, the heat of reaction is strong, then. dehydrated by further heating and finally kept at about 250 ° for 11 / a to 2 hours. The escaping acid is recovered and can be used after replenishing what has been used. can be used for a new approach.

The dry residue is broken or ground and washed with hot Water leached several times. The alkalis contain almost all of the Ca.0 as calcium chloride and only a maximum of 1%: this entire P2 05.

The moist residue of 148 kg with 23.31 / o P.0. and 24.20 / 0 A1203 contains both components in a completely alkali-soluble form, and will. in familiar Way processed.

Part of the residue, dried at 105 °, shows the following composition: P205 ........................ 39.48% Fe. 0, ....................... 12.5 0/0 A12 03. . . . . . . . . . . . . . . . . . . . . . . 41.2 0/0 Ca b. . . . . . . . . . . . . . . . . . . . . . . . . 0.310 / 0 The discharge effect on Ca0 is thus 97.651 / o. Example 2 200 g of the alumina iron phosphate described in Example 1 are slowly introduced into 200 g of 37% strength hydrochloric acid, the mass heating up vigorously with vigorous foaming. The mixture is evaporated to dryness with constant stirring and then heated to 300 ° for about 1 hour. The acid remaining for the formation of Caleiumch, lo, rid escapes and is recovered. The residue pre-treated in this way is leached several times with hot water and thereby freed from the calcium chloride formed.

After drying: at 105 °, 170 residue remains with a Content of 1.175% Ca 0. This result corresponds to a degree of leaching of Ca 0 of 90.61 / o. Example 3 In 33 l of a preheated 62% strength nitric acid while stirring vigorously. portions: 30 kg of the alumina iron phosphate mentioned in Example 1 registered. After the end of the entry, the reaction mixture is 1 hour at temperatures held around 110 °., A large part of the excess acid distilled off.

The cooled cake; is broken and 2 hours to 260 up. 280 ° heated, whereby it disintegrates finely and the remaining excess acid as well nitrous gases escape, which are also recovered.

The reaction product is repeatedly leached with hot water and delivers an end product which still contains 0.5% Ca0 to 37.50 / a P205. The salary of the end product, nitrate nitrogen is 0.04% N2. Losses at P20 $, A1203 and Fe203 do not occur in the washing waters. The leaching effect on Ca0 is 96 ° / o.

Claims (1)

PATENT CLAIM Process for decalcifying lime, clay and iron containing. Phosphates by treating with acids, characterized in that da.b3 the rock phosphates with excess, preferably two to five times the amount an acid that forms soluble calcium salts, then to temperatures above 110 °, preferably to 150 to 300 °, are heated and the dry reaction products separated by leaching with water from the calcium salt formed and the residue in a manner known per se on trialkali phosphates, clay and / or Eisencxvdhz-drat is further processed. References contemplated: United States Patent Specification No. 2,586,545.