HGI Hardgrove Grindability Index Tester

DESCRIPTION

The HGI (Hardgrove Grindability Index) Tester is a test instrument designed to determine and calculate the grindability index value of coal with high accuracy. Manufactured in full compliance with ASTM D409/D409M – 24 standards or ASTM D5003/D5003M − 23 standards, this device ensures precise measurement of coal sample grindability, providing reliable data for process optimization in the coal, energy, cement, and mining industries.

This tester operates by applying a standardized grinding force on a coal sample and measuring its ability to be pulverized under controlled conditions. The results provide essential data for coal classification, process efficiency, and industrial combustion applications.

This tester operates by applying a 29 ± 0.2 kg (64 ± 0.5 lb) grinding load on a 50 ± 0.01 g coal sample, using 8 steel balls (25.4 ± 0.13 mm diameter each). The grinding process occurs at a controlled 20 revolutions per minute, completing 60 ± 0.25 revolutions per test cycle. The results provide essential data for coal classification, process efficiency, and industrial combustion applications.

TECHNICAL DATA

Fields of Application Coal Mining and Processing, Power Generation, Cement, Metallurgical Industry, Research and Development

Application Grindability Testing, Quality Control, Process Optimization

Standards ASTM D409 & ISO 5074 & ASTM D5003/D5003M − 23

Power and Electricity 0.25 kW, 220 V, 1p, 50 Hz

Compatible with various voltages.

Dimensions 420 x 470 x 550 mm

Weight 74kg

🔹 Additional reference samples for calibration (4x1kg)
🔹 Additional Sieves ISO 3310-1/2 with square apertures:
16 mm
4.75 mm
2.36 mm
1.18 mm
0.600 mm
0.075 mm

Applications

The HGI Tester is widely used in industries for assessing the grindability properties of coal samples, ensuring efficient milling and processing. Key applications include:

🏭 Power Plants: Evaluating coal suitability for combustion efficiency
⚒ Mining & Metallurgy: Analyzing material grindability for industrial applications
🏗 Cement & Construction: Assessing fuel characteristics for cement production
🧪 Research Laboratories: Providing critical data for academic and industrial research

Working Principle

The HGI Tester determines the grindability of coal samples by subjecting them to controlled grinding conditions. The procedure follows these steps:

Sample Preparation: A coal sample is sieved to obtain the required particle size fraction.
Loading the Sample: 50 grams of the prepared sample is placed into the grinding bowl.
Grinding Process:
- The upper grinding ring and 8 steel balls apply a controlled force to the sample.
- The grinding ring rotates at 20 revolutions per minute for a total of 60 revolutions.
- The applied grinding load is 29.0 ± 0.2 kg.
Post-Grinding Sieving: The ground sample is sieved through a 75 µm mesh to determine the fraction of fine particles.
HGI Calculation: The amount of material passing through the sieve is used to calculate the Hardgrove Grindability Index (HGI) value, indicating the ease of pulverization.

This method ensures standardized and repeatable grindability assessment, critical for industrial processes such as coal milling and combustion efficiency.

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