Druipina Irina

Faculty: Of Ecological And Chemical Technology
Speciality: Ecology in chemical techologies

Theme of master's work:

Research of possibility of aluminium sulphate reception from Donbass industrial wastes by acid methods

Scientific adviser: Belogurov Yurij, Matvienko Viktor

     In Donetsk region there have been accumulated about 3 billion tons of industrial wastes from various enterprises. These are pedigree sailings of collieries and dressing factories, high-ash slims of coil-benefication, ashes-cinders of power stations, clay overburden breeds, waste from chamotte manufactures etc. Such pollutions wastes contain considerable quantity of valuable components which can be extracted by processing. In particular, the above listed high-silica industrial wastes contain a significant amount of aluminium compounds and can be considered as potential aluminium-containing raw materials.

The raw materials characteristics

     The purpose of the present work is studying the possibility of aluminium extraction in the form of various compounds from Donbass industrial wastes.
    All  known methods of allocation of aluminium extraction from high-silica raw materials can be divided into two big groups: alkaline and acid. Using alkaline methods makes aluminium converted into water-soluble aluminates. In most cases processing such raw materials is connected with big power expenses and considerable quantities of additional reagents. Their efficiency sharply falls with an increase in silicon concentration and reduction of aluminium maintenance. Acid methods make it possible to receive water-soluble aluminium in the form of salts corresponding acids. In case of processing industrial high-silica waste preferable are acid methods, in particular, sulphuric-acid method. Interest to sulphuric-acid method is caused with reduction of prices on sulfuric acid.
     There are two versions of sulphuric-acid method. According to the first one preliminarily clay raw materials crush are burnt at temperature 650-800°С and processed at temperature 100-105°С within several hours wiht the concentrated water solution of sulfuric acid. Thus we receive a solution of aluminium sulphate which can be evaporated in oder to receive crystal aluminium sulphate. According to the other crushed aluminium-containtivy raw material crush is frit with sulfuric acid at temperature 350-400°С. Thus it can be used as a crude coagulant in processes of water preparation or for reception of line aluminium sulphate. In our opinion, the latter method has certain advantages as compared with the first one as it is characterised by smaller power expenses, smaller volumes of material streams in production and greater technological flexibility. The moust important indicators of aluminium sulphate quality are aluminium oxide content (at least 15 %) and iron mass fraction in the form of iron oxide (III), not exceeding - 0,3 %.
     For acid fritting there has been chosen a breed from "Donkerampromsyrya" enterprise engaged in production nonmetallic minerals. Processing of Toretsky deposit of fire-clay and refractory clay is conducted. Balance stocks of the deposit are estimated at 16,9 million tons, 500-600 thousand tons are annually. Various layers of the deposit contain of 15-33 % of Al₂O₃, and Fe₂O₃ from 0,9 to 2.3 %.
     In our experiments processing used the breed content Al₂O₃ and Fe₂O₃ being accordingly 24 % and 0,9 %. Before fritting the breed was crushed and mixed up with 86 % sulfuric acid. Breed fritting passed in a during of 30 minutes at temperature about 350°С, while insignificant quantity of gases was observed. As a result of this process a cake was obtained which can be easily split up. It is possible to use the obtained cake as crude coagulant for water preparation, or to get Al₂(SO₄)₃•12H₂O salt. For this the cake should be lixiviated with hot water in the proportion 1:4, the fine-dyspersated suspension is filtered, and then the filtered solution is evaporated till in oder to form crystal salt.
     The chemical analysis of the obtained salts on content the iron and aluminium maintenance and the maintenance sulphate ion has been. Photocolorimetric method of iron definition and fullymetric method of aluminium content has been used, as well gravimetric method of for a sulphate ion.
    According to the preliminary data oxide iron concentration in the product exceeds the admissible. It means that additional puring of iron connections is required. However, even such product can be used as effective coagulant for water treatment as an iron sulphate also has a high coagulation effect.
     Further tests fritting from clay layers of other structure other industrial waste with sulfuric acid is planned.