A process for fine ground and ultrafine ground calcium carbonate produced in a ufg dry grinding mill in closed circuit with a high efficiency air classifier.
How To Grind Calcium Carbonate
The feed material is fed pneumatically through a venturi eductor into the mill. The particles are pulverized by a high speed agitated grinding media. The grinding media can be stainless steel, chrome steel, alumina or zirconia. The micronized particles are entrained in the air stream and exit the mill in a high efficiency air classifier. The on size particles are separated and the oversize returned to the mill for regrinding.
This grinding process is suitable for calcium carbonate, marble and limestone grinding down to 1 micron average particle size
Fine Grind Calcium Carbonate
- Increased green strength (3 & 7 day) by 10%
- Comparable or increased strength @ 28 & 90 day
- Reduced set times – initial set times reduced by 11%, final set times reduced
- by 14% – acts as an accelerator
- Improved slump, less water/cement ratio, reduced admixtures
- Significantly reduced bleedwater
- Increased density, reduced permeability, improved durability
- Flexural strength was not tested but should increase significantly
Typical Properties
| Source | SylacaugaAL | Marble HillGA | Baltimore, MD |
| Brightness (Hunter Y) | 95 | 93 | 92 |
| CaCO3 (%) | 95 | 95 | 90 |
| Acid Solubles (%) | 2 | 3 | 3.5 |
| SIO2 (%) | 0.3 | 0.3 | 0.8 |
| Moisture (%) | 0.15 | 0.15 | 0.15 |
| Plus 325 mesh (%) | 0.005 | 0.005 | 0.005 |
| Median Particle Size (microns) | 3 | 3 | 3 |
| Hardness (Mohs) | 3 | 3 | 3 |
| Refraction Index, mean | 1.6 | 1.6 | 1.6 |
| Specific Gravity | 2.7 | 2.7 | 2.7 |
| Solid density (lb/gal) | 22.7 | 22.7 | 22.7 |
| Bulk density (lb/ft3) | |||
| Loose | 40 | 40 | 40 |
| Packed | 65 | 65 | 65 |