Product Overview
The Hardgrove Grindability Index Tester determines the grindability of bituminous coal and anthracite. Results are expressed as the Hardgrove Grindability Index, or HGI; a higher value indicates that the coal is easier to pulverize. The test data provide useful input for the design, selection, and operation of coal pulverizing equipment. The supplied specification states that the instrument was designed in accordance with GB 2565-87 for the Hardgrove method and incorporates updated handling and electronic revolution-counting features.
How It Works
A prepared coal sample within a specified particle-size range is placed in the grinding bowl and subjected to a standardized grinding load. The spindle rotates the grinding ring and eight steel balls at 20 rpm. After 60 revolutions, the instrument stops automatically. The ground sample is then sieved and weighed, and the Hardgrove Grindability Index is determined using the applicable calibration relationship or chart.
Structure and Operation
The instrument consists of an upper-bowl lifting mechanism, worm gearbox, transmission gears, grinding ring, steel grinding bowl, motor, magnetic revolution sensor, and intelligent revolution controller. A push-up bowl mechanism beneath the grinding assembly reduces manual lifting effort. The LCD displays the accumulated revolution count, and the controller stops the machine after the preset 60 revolutions. An emergency stop is available, and the count can continue after restarting if required.
Key Advantages
Controlled spindle speed, total load, ball size, and revolution count support repeatable HGI testing under defined laboratory conditions.
A magnetic sensor and digital controller count spindle revolutions, display progress, and stop the instrument automatically after 60 revolutions.
The mechanical lifting mechanism raises the grinding bowl into position, reducing the physical effort associated with manual bowl support.
The integrated drive, grinding, loading, and control assemblies provide a compact footprint and straightforward operation for routine coal laboratories.
Applications
Model Selection Guide
| Parameter | Specification |
| Spindle Speed | 20 ± 1 rpm |
| Preset Operating Revolutions | 60± 0.25 revolutions |
| Total Grinding Load | 284 ± 2 N |
| Grinding Balls | 8 steel balls, each 25.4 mm in diameter |
| Motor Model | JW5614 |
| Motor Power | 90 W |
| Motor Speed | 1400 rpm |
| Power Supply | Three-phase 380 V |
| Instrument Weight | 85 kg |
| Dimensions L x W x H | 365 x 425 x 443 mm |
