Industry News

Leading Edge Materials Completes First Phase to Manufacture Expandable Graphite

Published on 2019-09-03. Author : SpecialChem

Leading Edge Materials has announced the successful completion of the first phase of test work to manufacture expandable graphite using material from the Woxna graphite mine in Sweden. Expandable graphite provides potential for creation of additional value-added products from Woxna.

Expandable Graphite - Key Points:


  • Expandable graphite has been produced and tested, with its performance in-line with commercially available materials currently in the market;
  • Expandable natural graphite is a critical industrial material, with a significant and growing market for fire resistant building products, textiles and graphite foils;
  • The manufacturing methods tested did not require the use of toxic chemicals;
  • Pricing of expandable graphite is based on flake size, expansion ratio and purity, and lies in the range of USD 2000 – USD 4000 per tonne;
  • Provides the potential for creation of additional value-added products from the Woxna graphite mine in Sweden;

Research was completed in Germany with leading consultancy ProGraphite GmbH (“ProGraphite”). ProGraphite used run-of-mine +80 mesh (>180 micron) material from the Woxna mine to test a range of standard process variables. Testing demonstrated that a combination of sulphuric acid and potassium permanganate delivered optimal results, expanding up to 215 ml/g (480 times) when heated to 1000°C.

This degree of expansion is in line with expandable graphite products available in the market today. Additional process optimization and product improvement is anticipated through further research. The methods tested did not require the use of toxic chromium, lead, or bromine-bearing chemicals that are used in the manufacture of some Chinese expandable graphites.

A High Value Application for Graphite Flakes

Mr. Mark Saxon, Interim CEO stated, “Expandable graphite is a high value application for graphite flakes that are larger in size and of a lower purity than that required for battery anode materials. The work completed by ProGraphite using stockpiled material from the Woxna mine has demonstrated that our material expands in line with current commercial products, using a process that does not require any toxic chemicals. We will continue to pursue this research in parallel with our battery anode materials, which provides potential for additional value-added products.”

Expandable graphite exploits the remarkable anisotropic property of natural flake graphite. Mild non-toxic chemicals (in this case sulfuric acid) are positioned between individual graphite flakes, which when exposed to heat converts from a solid or liquid to a gas phase causing a dramatic accordion-like expansion.

Expandable Graphite Applications

Expandable natural graphite is a critical industrial material, with a significant and growing market. Current market size is estimated to be 70,000 to 80,000 tons per year, with approximately 45% of demand coming from manufacture of fire-resistant materials. Other market segments include flexible foils, conductivity additives, and a small volume as a graphene manufacturing pre-cursor.

Demand for expandable graphite for fire resistant building products and textiles are both substantial and fast growing. When incorporated in building materials and plastics, the dramatic expansion on heating greatly reduces product flammability, as the expanded graphite forms a protective barrier in the event of fire. Globally, governments are moving to restrict use of flammable building materials, with the China Building Materials Application Technology Research Institute stating in 2018 “China needs 4 0 million tons of fire-retardant building materials per annum, which will contain 5% expandable graphite.”

Source: Leading Edge Materials
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