SU38137A1 - The method of obtaining aluminum alum - Google Patents

Description

Zaglik alunites are the basic aluminum sulphate salt of potassium sulphate and sodium KjSO. . А12 (8О4) з 4 А1 (ОН) з, interspersed in flint. In addition to alunite, this rock also contains rosit-iron-potassium sulfate.

Extraction of alum from this breed was made many years ago. It is known that alum was produced in Zaglik at the beginning of the past centuries.

The applied method was to roast the rock and extract alum, to treat the rock with water and subsequent crystallization. However, the conditions of the regrinding and crystallization were not specified, which led either to low yields of alum from a taken rock, or to a completely vain lengthy leaching and crystallization process.

The chemistry of the process consists in the burning of alunite, in which the decomposition of its molecule (dehydration) occurs with the excreta; the presence of hydrated water by the reaction:

1) K2 SO, .A1, (SO. 4A1 (OH)

 K, SO, A, (SO,), 2 A, 0, +.

(58)

This reaction starts at about 450 ° and is especially accelerated at 550-600 °.

During long-term roasting of alunite, especially at high temperatures, starting from 550-600, further decomposition of the obtained chemical compound occurs with the release of sulfur dioxide.

2), -M, (80,) s-2 A1.0z.,

The second reaction is harmful, since as it proceeds, aluminum sulphate decomposes into insoluble alumina, and therefore alum flow decreases.

Thus, the purpose of roasting in the production of alum is the complete dehydration of alunite with minimal decomposition of aluminum sulphate.

The process of extracting alum from Zaglik alunite, which was recently adopted at the Zaglik Alum Plant, prior to its conservation, consists in the following (Berzelius-Nalchagarov Zuglik Alunite Deposit and Alum Production, 1926)

p. 17). The ore was crushed on Blackgr; crushers, then fed to the Malatra-type kiln kiln, after calcination, the rock was crushed again with a crusher and dried with water for 7–9 days to leach the alum. The final leaching of alum was carried out in Chanks apparatus at a temperature of 60–70 °. The solution was then boiled down to 35 ° B and crystallized.

Concerning the firing temperature there are conflicting opinions, the court on the work done on alunites.

Dementiev and Lutsenko, in his work, “Conditions for extracting alum from alunitized Zaglik rock (Lime at the Azerbaijan Petroleum Institute, vol. 2 (9), jubilee, 1931, p. 110) stop at roasting at a temperature of 600 ° for two hours, and the burnt ore is immediately released into the water. Cameron (Journal. Ind. And Chem. March, 1932) burns alukite at a temperature of 500 ° in view of the beginning decomposition of ore to form sulfur dioxide. Swartz also offers the same firing temperature (Veg. D. D. Chem. Ges., Berlin, 17, 1884, 2887). Vinec (Bull. Soc. Chim. 25, 1876, 428) describes a method of treating Hungarian alunite (in Beregastre), where, in contrast to the above, higher temperatures are used. Alunite was calcined for four hours in a layer 8 cm high at a temperature of 700-830 °; however, 4% SOj is released due to decomposition of the rock.

Guyot (Cheni. News 53, 27; 1886,2064) Jahresbericht iiber die Fortschritte der Chemie adheres to the same high firing temperatures, which indicates that at a firing temperature of 800-900 °, better yields are obtained than at lower ones. The burning time is given to them for two hours (Lyubavin, Technical Chemistry, Alum).

The authors, after examining the influence of the firing temperature on the output of alum from the Zaglik deposit, found below are some of the most characteristic data collected in the table; showing the relationship between the air temperature, the time of the experiment and the transition to the solution of alunite sulphate salts as a percentage of their theoretical content.

Output in%

a№.

Time

t ° firing

61.4

6 o'clock

1 2 3 4 5 6 7

550

bO.S 600 g. 97.0

40 mil 700 95.0 20 „750 85.0 15„ 800 86.0 8PO 20 „Ы.9 850 10„

It turns out that the best results are obtained at a temperature of 700-750 ° and a firing time of 20-40 minutes. You have also clarified that when roasting at a temperature of 700 °, at the beginning there is a very fast dehydration of alunite, and only after release of water, which occurs 30-35 minutes after the start of roasting, the very slow decomposition of the alunite sulfate begins. Thus, the authors believe that the dehydration of alunites at a temperature of 700 ° ends very quickly, and it does not completely require a long firing at a temperature of 600 ° (Dementiev) or at a temperature (Guyot); the latter also leads to the inevitable decomposition of alunite sulphate salts.

At higher calcining temperatures than 700-750 ° C, decomposition of Alg (SO4) 3 starts, before the onset of complete dehydration, leads to inevitable loss of meters.

In addition, it was found out that when leaching with heating, hydrolysis of those basic aluminum salts occurs, which go into solution during the leaching of alunite and precipitate, why leaching is better to produce without heating, but with occasional agitation of the mixture (by air); at the same time, almost complete leaching of alunite sulphate salts occurs within one day.

Thus, the difference of the proposed method of extracting alum from alunite from the previously proposed method consists in using: short roasting at a temperature of 700-750 ° for 0-10 minutes of 2-6 hours, thereby saving fuel for roasting the rock. In addition, calcined aluvit is thrown into hot water by hot water and Vlschelyachy 1tsl while stirring with air for 1 day; one day, while the previously proposed methods provided for leaching for 9-10 days or for monthly keeping of the rock.

An example of the method. Alunite ore is crushed by crushers according to grain size of 2-3 mm. The ore is then fed to a hot oven at 700 ° C and fired for 35-40 minutes. After this time has elapsed, the incandescent ore is released into cold water, to which the mother liquor from alum crystallization is added, and leached for 24 hours with occasional stirring of air from the compressor.

As a kiln, you can use any kiln guaranteeing kiln conditions, such as the Aletra type butt kiln, which is used in the Zaglik Quasdog plant.

Leaching can be performed by the method p; yutivoto: a, by processing fresh portions of alunite with more saturated solutions.

After leaching, the solution is fed to the precipitate; For evaporation, it is possible to use any alumina production evaporators, in the case of a high-capacity plant, Tsani-type tubular crystallizers (with corresponding insulation) or a multi-body evaporator.

After evaporation to 35 ° V, the solution goes to crystallization. The resulting mother liquor is returned to leaching (this becomes effective due to the fact that the alum solutions obtained are pure of iron, since rozite decomposes into iron oxide when the rock is burned earlier than alunite).

When the solution is evaporated, a precipitate is formed of basic sulphate salts of aluminum, which are settled in intermediate stages before final discharge and can be used to produce pure alumina sulphate by treatment with sulfuric acid.

The subject matter of the invention.

The method of producing aluminum alum from alunite, characterized in that the alunigovoy ore is crushed to a size of 2 --- i mm, is burned at a temperature of 700-7oO for 35-40 minutes, the red-hot ore is introduced from the furnace into water, in which leaching is carried out t during the day with agitation by air and in the cold.