A 125-year Old Global Pollution Problem
The Bayer Process
In 1887 Carl Josef Bayer invented the “Bayer Process,” which is used in most alumina refineries to separate alumina from bauxite. The process typically uses caustic sodium hydroxide of pH above 13, heated with bauxite to separate alumina. Alumina is the raw material for aluminum production by electrolysis. Alumina refining takes place in 30 countries.
- Alumina, or “aluminum oxide” is a white granular material, a little finer than table salt.
- The Bayer refining process, used by almost all alumina refineries worldwide, involves four steps: Digestion, Clarification, Precipitation, and Calcination.
- To refine alumina from bauxite, the ore is ground and mixed with lime and caustic soda, pumped into high-pressure containers, then heated up to 140 C or 240 C or 280 C depending on the mineralogical composition of the raw material.
- The aluminum oxide is dissolved by the caustic soda, then precipitated out of this solution, washed, and heated to drive off water.
- What is left is the white powder called alumina, which is then transformed into aluminum metal via electrolysis, i.e. the smelting process.
- Red Mud (RM) or Red Sludge is a toxic by-product of this refining process.
The Problem – Red Mud Disposal
- A typical alumina refinery produces one to two times as much red mud as it does alumina.
- Presently, there is approximately 2.5 billion tons of Red Mud disposed of in man-made unreinforced ponds or lakes with a pH exceeding 11.5 from all of the 30 alumina producing countries combined.
- More than 80 million additional tons are produced annually. As the strength of environmental regulations increase, the Red Mud disposal status quo, of having millions of tons in man-made lakes, is becoming untenable.
- Red Mud is composed of a mixture of solid and metallic oxide bearing impurities, with 5-20% caustic residual (sodium hydroxide) which presents the aluminum industry with its single most critical disposal problem.
- In addition to the up to pH 13 caustic residual, left from the refining process, there is iron and other materials in red mud including: silica, unbleached residual aluminum, and titanium oxide.
- Red Mud cannot be disposed of easily and represents an enormous environmental and land use problem for the industry and communities, as it takes up land area that can neither be covered over and built upon, nor farmed, even when dry.
- Red Mud is highly caustic with a pH ranging from 11.5 to 13. Environmentally acceptable levels for pH are between 7 and 9. Stored in mountainous heaps and lakes of red toxic material is an unlikely resource, untapped until now.
The blight that is Red Mud (RM) is now a green resource. The ParaTech process addresses all of the Red Mud disposal issues associated with human injury and environmental damage.
A New Solution To An Old Problem
ParaTech Global has a financially feasible solution to 125-year-old disposal problem.