SDHG60a Hardgrove Grindability Index Tester

The SDHG60a Hardgrove Grindability Index Tester is designed to determine the grindability of coal and other applicable solid-fuel samples by the Hardgrove method. It is suitable for laboratories in the coal, power generation, metallurgy, petrochemical, cement, environmental monitoring, geological exploration and research sectors.

The instrument applies a standardized grinding load of 284 ± 2 N to a 50 g sample and completes 60 revolutions at 20 ± 1 r/min. Its microcomputer-based control system automatically manages grinding-bowl lifting, load application, rotation counting and cycle completion, minimizing manual intervention and improving operational consistency.

The SDHG60a can be connected to an electronic balance for direct transfer of weighing data. Based on the established calibration curve, the system automatically calculates the Hardgrove Grindability Index (HGI), stores the test record and prints the final result. It is designed in accordance with MT/T 230, with measurement precision meeting the relevant requirements of applicable international standards.

Key Features

Fully Automated Grinding Cycle

After the grinding bowl is loaded, the instrument automatically raises the bowl, applies the specified grinding force, starts rotation, counts the revolutions and stops after completing the preset 60-revolution cycle. The bowl is then automatically lowered for removal.

Standardized Grinding Conditions

The instrument maintains the critical mechanical conditions required for Hardgrove testing, including:

  • Spindle speed of 20 ± 1 r/min
  • Grinding load of 284 ± 2 N
  • 60-revolution grinding cycle
  • 25.4 mm grinding balls
  • 50 g grinding-bowl capacity

These controlled conditions help ensure consistent and repeatable test performance.

Automatic HGI Calculation

The built-in calculation program processes sample mass and sieving data and automatically determines the HGI value according to the stored calibration relationship, reducing manual calculation errors.

Calibration and Linear Regression Functions

The system supports calibration using certified reference coal samples. It can automatically calculate and display the:

  • Linear regression equation
  • Correlation coefficient
  • Standard deviation

This simplifies instrument verification and calibration-curve management.

Direct Balance Data Transfer

An electronic balance can be connected directly to the tester. Stable weighing results can be transferred to the instrument without manual entry, improving data integrity and laboratory efficiency.

Intelligent Data Validation

The software checks whether entered weighing data meet the method requirements. It provides prompts when sample mass or mass-balance values fall outside the specified limits, helping operators identify invalid tests before results are reported.

Integrated Data Management

Test results are automatically stored in the instrument. Operators can search, review, delete and print historical records by sample number, date or record ID.

Real-Time Status Monitoring

The LCD interface continuously displays operating status, bowl position, grinding progress and revolution count, allowing the operator to monitor the entire test cycle clearly.

Fault Alarms and Emergency Stop

The instrument monitors the lifting and rotation mechanisms and provides audible and visual alarms for conditions such as lifting timeout, positioning failure or rotation-counting faults. An emergency-stop function allows the grinding cycle to be interrupted when necessary.

User-Friendly Operation

The combination of an LCD screen, membrane keypad and clearly structured software menus provides straightforward access to calculation, data inquiry, calibration, system settings and help functions.

Applicable International Standards and Methods

 

StandardStandard TitleApplicable Samples
ISO 5074Hard coal – Determination of hardgrove grindability indexCoal and coke
ASTM D409Standard test method for grindability of coal by the hardgrove-machine methodCoal and coke

Specifications

Spindle Speed: 20 ± 1 r/min

Grinding Revolutions: 60 revolutions

Applied Grinding Force: 284 ± 2 N

Grinding Bowl Capacity: 50 g

Grinding Ball Diameter: 25.4 mm

Maximum Power: 0.17 kW

Power Supply: AC 220 V ± 10%, 50 Hz ± 1 Hz

Instrument Weight: Approximately 88 kg

Sample Requirements:

  • Sample Particle Size: 0.63–1.25 mm
  • Test Portion: 50.00 ± 0.01 g
  • Grinding Cycle: 60 ± 0.25 revolutions, approximately 3 minutes
Application Notes

We are compiling our practical application experience into a growing collection of technical articles that will be published here regularly.

If you have an immediate analytical challenge before then—whether in mining, energy, advanced materials, or PFAS analysis—contact the Sundy Technology Application Laboratory. We provide customized method development, application optimization, and technical support to help you achieve reliable analytical results.

On-site Photos
Videos

Our video library is currently under development, featuring product operation tutorials, application demonstrations, and technical explainers. Stay tuned for regular updates.

Customer Testimonials
We have provided a complete set of Sundy testing solutions, including bomb calorimeter, sulfur analyzer, and thermogravimetric analyzer, to the fuel analysis laboratory of Kavçim Cement, a leading integrated cement plant on Turkey’s Black Sea coast. Sundy’s standardized instrument performance bring outstanding practical value to end users. The upgraded solution significantly simplifies daily operations, lowers manual intervention and maintenance costs, and unifies data consistency for routine fuel analysis.We are very satisfied with Sundy’s product quality and technical support, and will continue to promote and recommend Sundy analytical instruments for more industrial laboratory projects in Turkey.
Dr. Karahan, POTANTEK
After more than 10 years of continuous cooperation and market verification, we confirm that Sundy’s products, especially its automatic calorimeters and elemental analyzers, have high precise temperature control, accurate testing results, and ultra-low failure rate. All products are fully compliant with international ISO and ASTM standard, completely meeting the testing demands of coal laboratories, power plants, industrial enterprises, universities and scientific research institutions.We highly recognize Hunan Sundy Science and Technology’s strong production capacity, standardized quality management system, professional technical support team and excellent business credibility. In all our cooperation cases, Sundy has always demonstrated professionalism, reliability and a customer-oriented service attitude.
Dr. Kim, YEONJIN
FAQs

The SDHG60a determines the Hardgrove Grindability Index (HGI) of coal. HGI indicates the relative resistance of a coal sample to pulverization under specified grinding conditions.

The instrument is intended for testing bituminous coal and anthracite prepared in accordance with the applicable Hardgrove test procedure. The manual does not specify its use for lignite or highly weathered coal.

The instrument is designed according to MT/T 230-2005, and its measurement precision meets the relevant requirements of GB/T 2565-2014 for determining the grindability index of coal by the Hardgrove method.

A prepared coal sample within the specified particle-size range is ground under a standardized load and for a fixed number of revolutions. The ground sample is then sieved and weighed. The mass of material passing the specified sieve is converted into an HGI value using an established calibration equation.

A higher HGI value indicates that the coal is easier to grind under the specified test conditions. Conversely, a lower HGI value indicates greater resistance to pulverization.

The coal used for the HGI test must be prepared to a particle-size range of 0.63–1.25 mm. Material smaller than 0.63 mm must be removed before the test portion is weighed.

The required test portion is 50.00 ± 0.01 g after removal of material finer than 0.63 mm. The instrument software checks the entered sample mass and issues a warning when it falls outside this range.

The principal grinding conditions are:

  • Spindle speed: 20 ± 1 r/min
  • Number of revolutions: 60 ± 0.25
  • Vertical grinding force: 284 ± 2 N
  • Grinding-ball diameter: 25.4 mm
  • Grinding-bowl capacity: 50 g

The grinding stage takes approximately 3 minutes at the specified spindle speed. This refers only to the instrument grinding cycle and does not include sample preparation, sieving, weighing or result processing.

After the operator places the grinding bowl on the lifting platform and presses the start key, the instrument automatically raises and positions the bowl, starts the rotating mechanism, counts the revolutions and stops when 60 revolutions have been completed. The bowl is then automatically lowered for removal.

Yes. A compatible electronic balance can be connected to the instrument. Once the weighing result is stable, the operator can transmit the value directly to the selected data field, reducing manual entry and transcription errors.

According to the manual, the balance serial communication parameters are:

  • Baud rate: 9600
  • Data bits: 7
  • Stop bits: 1
  • Parity: Even
  • Data output: Manual transmission after stabilization
  • Line format: 16 characters

The operator enters or transfers the original sample mass and the relevant sieve-retained or sieve-passing mass. The instrument then applies the stored linear regression equation obtained from reference-coal calibration and automatically displays the calculated HGI result.

The software checks whether:

  • The initial test-portion mass is within 50.00 ± 0.01 g
  • The total recovered mass differs from the original sample mass by no more than 0.5 g
  • Conflicting retained-mass and passing-mass fields have not been entered simultaneously

When the data do not meet these conditions, the system displays an appropriate warning.

The test must be repeated when the sum of the mass retained on the 0.071 mm sieve and the mass passing the sieve differs from the original test-portion mass by more than 0.5 g. This indicates excessive sample loss or an unreliable mass balance.

Certified or recognized grindability reference coal samples are tested, and their standard HGI values and corresponding sieve-passing masses are entered into the calibration interface. The system then calculates the linear regression equation used for subsequent HGI determination.

Using two to four sets of calibration data, the instrument can automatically calculate and display the:

  • Linear regression equation
  • Correlation coefficient
  • Standard deviation

The manual requires calibration with grindability reference coal at least once per year. Additional calibration should be performed after a change of operator, replacement or repair of the instrument or test sieves, or whenever the validity of the HGI results is in doubt.

The SDHG60a monitors the lifting and rotating mechanisms. Alarm messages may be generated for conditions such as:

  • Lifting-motor startup timeout
  • Lifting or positioning timeout
  • Rotation-motor timeout
  • Failure of the revolution-counting sensor or positioning component

The alarms are accompanied by an audible indication to help the operator identify abnormal operation.

After each test, the grinding bowl, grinding ring and steel balls should be thoroughly cleaned to prevent sample carryover. The instrument should be disconnected from the power supply and cleaned after use. When the grinding components will remain unused for an extended period, appropriate rust-prevention measures should be applied.

Related Products

SDAF1200b Ash Fusion Tester

SDBS200 Flash Point Tester

SDAC1200 Bomb Calorimeter

Have Questions? Contact Us Directly

Share your application details and our team will recommend a suitable configuration.

Technical Consultation

Get professional advice for your application and project.

Quotation Request

Request a detailed quotation quickly and easily.

Application Support

Find the best solution for your
specific application.

Spare Parts Inquiry

Inquire about parts, availability and delivery.