COLLOIDAL AND CHEMICAL PROPERTIES OF BENTONITES FROM THE ORENBURG REGION

When assessing the quality of bentonite, the following properties must be taken into account: content of the bentonite-forming mineral montmorillonite or beidellite; colloidality of bentonite with the formation of a stable suspension of fine flexible particles uniformly enveloping the grains of the ore concentrate; thixotropic properties determined by the ratio of rheological properties in the suspension-gel system; effective viscosity; heat resistance of bentonite with the ability to retain binding properties at the stages of heat treatment up to 5000C; swelling, as one of the most important features used in pelletizing. In this paper, studies were conducted on the study of the material composition and rheology of Orenburg bentonites to determine the possibility of using them as clay powders for the petrochemical industry. To determine the material (mineralogical, chemical) composition of the initial components and intermediate modification products, the following were used: quantitative phase X-ray analysis using an Advin powder diffractometer, determination of cation-exchange capacity using a Kapel-205 capillary electrophoresis system, and titration and gravimetric methods. For bentonite clay raw materials, the testing program according to GOST 25796.0-83 - GOST 25796.5-83 "Clay raw materials in the production of clay powders for drilling fluids. Test methods" includes: determination of the yield of clay solution (GOST 25796.1-83); determination of modifiability indicators (GOST 25796.5-83). For testing, the initial clays were prepared to a particle size of no more than 0.25 mm with a residue on sieve No. 01 of at least 80%. According to rheology, the samples are characterized by a low yield of drilling mud (less than 4.5 m3/t). It is noted that the samples have a high modifiability index PM2 (more than 130 degrees), which characterizes them as easily modified clays and allows them to be classified as grade B-9. According to the analytical and technological tests, bentonites are characterized by a rich content of the montmorillonite component, more than 50%. High dispersion and rheological properties recommend the use of bentonite as clay powders in the petrochemical industry. According to the PM 1 and PM 2 indicators, it should be noted that bentonites respond well to modification with magnesite, but are not effective enough for modification with soda. Modification of bentonites of the Orenburg region with caustic magnesite with subsequent plastic mechanical activation can improve their rheological properties and use them as bentonite powders, which makes them more effective in various industrial applications. The original bentonite is characterized by a good specific surface with a mesoporous structure and can be used as a raw material for the production of adsorbents without modification. Based on the conducted studies, a certain reserve for further work on the development of technology for the production of modified clay powders has been outlined.