Coal Dust

Iron Casting Application

This fine, powdered coal has been used to improve the surface finish of iron and copper castings since the 1870s. Used in greensand and dry sand moulding, coal dust protects the mould surface against the action of molten metal. When the metal comes into contact with a mould surface containing coal dust, a gaseous envelope is formed, which resists the fusion of sand to metal. Additives like pitch, cellulose, and silica flour are used, depending on the metal cast.

  • Castings cool more slowly, preventing cracking
  • Coal dust increases both greensand and dry sand strength
  • Reduces expansion, scabbing, and metal penetration
  • Prevents sand burn
  • Imparts a cleaner finish
  • Aids in separation at knockout
  • Lessens rat tailing and other expansion defects
Coal dust contains low concentrations of trace metals, PAH, and sulphates.
  • Standard and Low-Ash formulations suitable for foundry use



African Pegmatite has two grades of Coal Dust available.

  • 100 Micron
  • Min. 23%-25% Volatile Matter
  • 14%-20% Ash
  • 3.5% Moisture
  • 100 Microns
  • Min. 34%-40% Volatile Matter
  • 10%-11% Ash
  • 3.5% Moisture
  • 0.6%-1% Sulphur

Data Sheets

Refractory Grade          

Foundry- Low Ash Grade

Foundry- Standard Grade

General Information

The quality of coal dust that’s suitable for foundry use should consist of finely crushed bituminous coal that’s free of foreign material.

Contamination of sulphur by the metal at the mould face can cause defects. Sulphur content of foundry coal dust should never be more than 10%.

Optimum levels of Coal Dust should be established by trial and always weighed and metered.

Appropriate proportion by weight of Coal Dust in greensand varies from 2%-3% for small castings and from 7%-8% for heavy work. Higher levels are sometimes used in special cases.

Effects of too much Coal Dust:

  • Grazed surfaces
  • Gas holes
  • Rounded edges
  • Misruns

A build-up of coal dust in sand can cause a blue skin on the casting, a decrease in permeability, and an increase in moisture requirement of the sand.


Choose the packaging and shipping arrangement that best suits your needs, from small packaging to bulk bags or custom sizes made just for you. We can accommodate virtually any size, from one metric ton to thousands.


We maintain competitive pricing in an effort to win and retain your business for as long as you need us. Our goal is to meet the needs of every customer, including those with special requests and demanding production schedules.

A 15-day general turnaround for manufacturing allows us to get your compounds to you as quickly as possible, so you can keep up with the demands of your business. Contact us to get in touch with a distributor in your area if you don’t have time to wait for materials.

We currently ship to 44 countries across the world and we’re happy to ship to yours, too. The dependable and professional logistics channels we have in place make it easy to offer great pricing and service regardless of your location.

African Pegmatite

With 48 years as professionals in mining and manufacturing, we have the insight, network, and experience to offer you the very best in quality, service, and efficiency. We’ve been accredited by the ISO 9001 since 2002 and have most recently met the 2015 standard.

We aim to provide the very best materials available to our customers, and become your one-stop shop for colourants, minerals, compounds, and more. Take a look at our general foundry page to see all the other foundry and supplementary products we have available.

If you’d like to become a distributor of African Pegmatite products, get in touch with us and we’ll customise an arrangement with you.