Within Zorka Keramika two branches are formed: Branch CLAY PIT DONJE CRNILJEVO, Donje Crniljevo and Branch CLAY PIT JADRANKSA LEŠNICA, Jadranska Lesnica.
The most significant advantage of our pits is the facts of having more kinds of clay in one place. According to experts analyses pits abound with reserves and the exploitation will be possible for next 15-20 years more. Considering the fact of having in first 5-10 m exploitation of the clay for brick production, and under - layers of white clay for tile production, clay pits are source of raw material for both brick production and tile production.
All clays in property of Keramika-holding d.o.o. are located in Upper Tamnava Tertiary Basin.
Their mineralogical composition represents mixture of kaolin-ilite-montmorionit clays, that determines their key properties like plasticity, foundry, drying properties, bending strength and color after firing.
Current products:
- Yellow–red brick-ceramic clay
- Grey-white ceramic clay
- Dark brick clay
- Homogenised clay for floor tiles
- Kaolinite granit (as welding flux in ceramics)
Application:
- Rough ceramic: in brick industry, ceramic canalization pipes, pottery;
- Fine ceramic: wall and floor tiles, toilet ceramics;
- Other: paper industry, rubber, fertilizers. Raw clay is additionally processed, minced, dried, micronized and milled, in order to be used in above mentioned fields. In certain amount clays are used in refractory products as firebricks, electrical power insulators, etc.
Yellow–red brick-ceramic clay
Main charasteristics:
Moisture by delivery: 17.0 - 19.0 % (depends on seasion)
Rest on the strainer from 63µm: 34.8 %
Chemical composition:
| Component | Bur. los. | SiO2 | Al2O3 | Fe2O3 | TiO2 | CaO | MgO | Na2O | K2O |
| Content % | 4.76 | 71.06 | 15.08 | 5.30 | 1.00 | 0.25 | 0.30 | 0.14 | 2.11 |
Mineralogical composition (Rõ analyses): mostly common quartz, minerals from the filosilikate group and smektit group in traces.
Charasteristics and behavior in proces of drying and burning:
- water needed for plastic processing: 30.25%
- plasticity by Pfefferkorn: 33.65%
- shrinking by drying process on 105°C: 6.46%
Klinkering temperature: > 1250°C
Sintering temperature: > 1250°C
Usage:
Mainly for brick industry.
Testing of burning the exploited sample:
| Temperature | Burning colour (CEC) | Tot. shrink. | Watter absorbtion | Apperance |
| 1250 °C | H-9 dark brick red | 12.64 % | 7.01 % | normal |
| 1170 °C | G-10 dark brick red | 11.48 % | 11.59 % | normal |
| 1100 °C | F-10 brick red | 9.57 % | 13.92 % | normal |
| 1000 °C | E-9 dark cream | 7.49 % | 18.43 % | normal |
| 930 °C | E-8 dark cream | 7.25 % | 19.11 % | normal |
Grey-white ceramics clay
Main charasteristics:
Moisture by delivery: 17.0 - 19.0 % (depends on seasion)
Rest on the strainer from 63µm: 8.59 %
| Component | Bur. los. | SiO2 | Al2O3 | Fe2O3 | TiO2 | CaO | MgO | Na2O | K2O |
| Content % | 6.05 | 65.98 | 20.79 | 1.88 | 1.33 | 0.34 | 0.75 | 0.12 | 2.48 |
Mineralogical composition (Rõ analyses): ostly quartz, minerals from the filosilikate group and smektit group in tracs.
Charasteristics and behavior in proces of drying and burning:
- water needed for plastic processing: 48.80%
- plasticity by Pfefferkorn: 54.40%
- shrinking by drying process on 105°C: 9.84%
Klinkering temperature: > 1125°C
Sintering temperature: > 1200°C
Usage:
For ceramics industry, floor and wall tiles with light brick colour.
Testing of burning the exploited sample:
| Temperature | Burning colour (CEC) | Tot. shrink. | Watter absorbtion | Apperance |
| 1250 °C | A-5 light grey | 19.06 % | 0.59 % | normal |
| 1170 °C | G-10 dark brick red | 18.72 % | 2.79 % | normal |
| 1100 °C | F-10 brick red | 18.35 % | 7.74 % | normal |
| 1000 °C | E-9 dark cream | 13.88 % | 17.01 % | normal |
| 930 °C | E-8 dark cream | 12.06 % | 20.62 % | normal |
Dark ceramic clay
Main charasteristics:
Moisture by delivery: 17.0 - 19.0 % (depends on seasion)
Rest on the strainer from 63µm: 5.96 %
Chemical composition:
| Component | Bur. los. | SiO2 | Al2O3 | Fe2O3 | TiO2 | CaO | MgO | Na2O | K2O |
| Content % | 12.09 | 50.08 | 29.29 | 1.51 | 0.70 | 1.47 | 0.73 | 1.78 | 0.32 |
Mineralogical composition (Rõ analyses): mostly quartz, clay minerals and felspats.
Charasteristics and behavior in proces of drying and burning:
- water needed for plastic processing: 29.70%
- plasticity by Pfefferkorn: 31.70%
- shrinking by drying process on 105°C: 6.50%
Usage:
As plastic material it is used for traditional ceramic products with long processes of burning, in refractory products, and as a filler in different industrial areas.
Testing of burning the exploited sample:
| Temperature | Burning colour (CEC) | Tot. shrink. | Watter absorbtion | Apperance |
| 1100 °C | B2/B3 white-cream | 8.69 % | 14.71 % | normal |
| 1000 °C | C2/C3 light yellow cream | 111.00% | 12.35 % | normal |
| 900 °C | C4 dark yellow cream | 14.00 % | 9.62 % | normal |
Homogenised clay for floor tiles
Main charasteristics:
Moisture by delivery: 17.0 - 19.0 % (depends on seasion)
Rest on the strainer from 63µm: 15.0 - 20 %
Chemical composition:
| Component | Bur. los. | SiO2 | Al2O3 | Fe2O3 | TiO2 | CaO | MgO | Na2O | K2O |
| Content % | 7.31 | 61.20 | 22.66 | 1.14 | 0.60 | 1.17 | 0.64 | 0.22 | 3.71 |
Mineralogical composition (Rõ analyses): mostly quartz, clay minerals and felspats.
Charasteristics and behavior in proces of drying and burning:
- water needed for plastic processing: 30.57%
- plasticity by Pfefferkorn: 32.52%
- shrinking by drying process on 105°C: 7.55%
Usage:
For ceramics industry, floor and wall tiles with light burned "brick" colour.
Testing of burning the exploited sample:
| Temperature | Burning colour (CEC) | Tot. shrink. | Watter absorbtion | Apperance |
| 1200 °C | C4 dark cream | 10.77 % | 0.30 % | almost sinterned |
| 1100 °C | C4 cream | 9.49 % | 3.56 % | normal |
| 1000 °C | B3/C3 yellow cream | 8.85 % | 9.08 % | normal |
| 900 °C | C1/D1 light cream | 5.45 % | 15.72 % | normal |
Kaolinite granit
Main charasteristics:
Moisture by delivery: 6.0 - 8.0 %
Rest on the strainer from 63µm: 75.0 - 85.0 %
Chemical composition:
| Component | Bur. los. | SiO2 | Al2O3 | Fe2O3 | TiO2 | CaO | MgO | Na2O | K2O |
| Content % | 3.20 - 4.10 | 63.0 - 66.0 | 19.0 - 21.0 | 1.50 - 1.65 | 0.20 - 0.23 | 0.85 - 1.25 | 0.20 - 0.30 | 1.75 - 2.70 | 5.40 - 6.45 |
Mineralogical composition (Rõ analyses): liskun, quartz, felspats and kalcit/dolomit.
Charasteristics and behavior in proces of drying and burning:
Klinkering temperature: > 1250°C
Sintering temperature: > 1250°C
Usage:
Exclusively as so called welding flux in ceramics industry.
Testing of burning the exploited sample:
| Temperature | Burning colour (CEC) | Tot. shrink. | Watter absorbtion | Apperance |
| 1200 °C | C4 dark cream | 5.23 % | 11.52 % | normal |
| 1100 °C | F12 dark brick red | 2.14 % | 14.87 % | normal |
| 1000 °C | E10 brick red | 1.05 % | 17.33 % | normal |
Contact:
ZORKA-KERAMIKA D.O.O.
Beograd-Novi Beograd
Bulevar Mihaila Pupina 10v/114
e-mail: s.djakovac@zorka-keramika.rs