JNARDDC with NALCO develops high strength ceramic balls from bauxite ore and flyash

The Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC) has developed a unique product; very high strength ceramic balls or granules made from one of the waste components (partially lateritized khondalite or PLK) of bauxite ore and flyash. The centre is in the process of developing these balls using another waste found in the ore saprolite.

These small balls (measuring just 0.5mm to 1.5mm) are technically called proppants and used by oil and gas industry in exploration for oil. The balls developed by JNNARDC cost just INR 2,000 per tonne, as compared to the as yet imported variety costing INR 20,000 per tonne. JNARDDC has already patented the technology.

The imported ceramic balls have an unusual strength of 10-12,000 pounds square inch (psi) and are used by the oil exploration industry to prevent fractures created during exploration from collapsing. The balls developed by JNARDDC at present have strength of 8000 psi but the centre is working on improving this strength further. The balls have been developed as an R&D product in collaboration with National Aluminium Company (NALCO) in Odisa.

"After realizing the huge market potential of this product, the two partners have decided to go ahead and set up a pilot plant at JNARDDC with support from NALCO and the department of science and technology, government of India. Otherwise also, it is worth trying to manufacture and market the product indigenously, it will be possible to manufacture it at ten times lesser cost," said Anupam Agnihotri, JNARDDC director. The centre will also try to involve an entrepreneur in setting up the pilot plant, so he could set up his own manufacturing unit later.

The biggest advantage of the technology is that the inferior quality components of bauxite ore will no longer be a waste. Agnihotri says that huge quantity of PLK, which contains about 25-30 per cent alumina, 20-35 per cent silica and 10-18 per cent iron, can be generated from the 6.3 million tonne of bauxite mined annually.

PLK is basically a very low grade bauxite ore, which remains unutilized. There is another major component of the bauxite ore, called as saprolite, which is always found at the bottom of any bauxite deposit and is a waste like PLK. Hence, another method of preparing the ceramic balls by combining PLK with saprolite and flyash along with a suitable binder can also be used alternatively.

"It will all depend on which combination gives maximum strength. In Gujarat, there are some manufacturers which make such balls using sand. But these balls have very low strength (just about 5,000 psi)," said Pravin Bhukte, principal scientist in bauxite division at JNARDDC and principal investigator of the project. The team involved in the project, besides Agnihotri and Bhukte, includes SP Puttewar, bauxite division head, and MJ Chaddha, alumina division head.

The process in a nutshell

• PLK is collected from bauxite mines (Panchpatmali mine of NALCO) and flyash from alumina refinery at Damanjodi
• Detailed characterization of PLK and flyash is carried out
• Two materials are finely ground (-25 microns)
• PLK and flyash combined using an additive
• Granules reduced to balls measuring 0.5mm to 0.25mm or 2mm to 4mm
• They are passed through rotary furnace with temperature from 1,200-1,300 degrees Celsius
• Calcination tests done for various parameters like temperature, time
• Granules tested for properties like resistance, sphericity, density, porosity, acid solubility and turbidity