BENTONITE POWDER FOR FORMING MIXTURES

The products are made from bentonite clay from the Askan deposit and are intended for use as a binder of the sandy-clay form in the foundry industry.
Technological processing of raw materials consists in the preparation of raw materials (stone separation, grinding, grinding of wet bentonite with additives), two-stage drying and subsequent grinding. Drying is carried out in a special dryer, ensuring the maximum possible preservation of the colloidal chemical properties of bentonite. The grinding of pre-dried raw materials is carried out in a roller-pendulum mill with a drying and classification of the resulting powder on a separator of a dynamic type.
To adjust certain consumer properties of the product, the raw material can be pretreated with inorganic salts of sodium, magnesium (activation) or organic reagents.
Grades of bentonite clay powder for molding compounds are produced according to the requirements of standards ГОСТ 28177-89, according to the requirements of the VDG P-69 Methodology, and also according to the Customer’s Specification.
Quality indicators of bentonite powder for molding compounds
№
Indicator
 Limits of opportunity
1.
Properties of the molding mixture according to the requirements ГОСТ 28177-89
1.1.
 Compressive strength in the wet state, kg.s./cm.2
0,9 – 1,5
1.2.
 Tensile strength at break in the zone of moisture condensation, kg.s./cm.2
0,020 – 0,040
1.3.
 Thermal stability
0,3 – 1,0
2.
 Properties of the molding mixture according to the requirements of the Methods VDG P-69
2.1.
 Compressive strength in the wet state, N./cm.2
7 – 11
2.2.
 Tensile strength at break in the zone of moisture condensation, N./cm.2
0,20 – 0,40
3.
 Properties of bentonite powder
3.1.
Humidity,% (ГОСТ 28177 – 89 )
8-12
3.2.
0,4mm sieve residue (ГОСТ 28177 – 89 )
0,0 – 0,0
3.3.
The residue on the sieve 0,16mm. (ГОСТ 28177 – 89 )
0,0 – 2,0
3.4.
Colloidal,% (ГОСТ 28177 – 89 )
25 -100
3.5.
Water absorption, units. (ГОСТ 28177 – 89 )
2,8 – 9,0
3.6.
Content of Fe2O3 (ГОСТ 28177 – 89 )
2,7 – 3,5
3.7.
Sulfur content in terms of SO3, % (ГОСТ 28177 – 89 )
0,1 – 0,2
3.8.
Carbonate content,% (ГОСТ 28177 – 89 )
1 – 3
3.9.
Methylene blue adsorption, mg eq.
(MBA-test , VDG P-69 )
300 – 410
3.10
 The residue on the sieve 0,063 mm.,%
10 – 25
3.11.
рН suspensions, units
9,5- 10,5
Bentonite powder for molding compounds is produced according to the requirements:
  1. Georgian Enterprise Standard СТП ГР 22983003-001-2017;
  2. Interstate standard ГОСТ 28177-89 «Bentonite molding clay. General technical conditions»;
  3. Techniques of the German Foundry Society МERKBLATT VDG P-69;
  4. Customer Specifications