“Red Mud” Research: The Bayer Method

The Bayer method of extracting alumina from bauxite is still the most cost-effective today. The insoluble material produced after the digestion of bauxite with sodium hydroxide at high pressures and temperatures to produce alumina is referred to as “bauxite residue” or “red mud” in this process. Because of the oxidized iron component in the product, it is referred to as “red mud.” According to reports, “red mud” is made up of a mix of compounds found in bauxite as well as compounds created during the Bayer process. Since the mixture has been exposed to the treatment of sodium hydroxide, red mud is found to be greatly caustic, having a PH ranging from 10.5 to 12.5.

Production of Red Mud

There is the production of about one ton of alumina from three tons of bauxite, and approximately one ton of aluminum is obtained from two tons of alumina (Annual report, 2012). The amount of alumina produced globally is about fifty-eight million tons, and India alone produces 2.7 million tons (Indian Aluminium Industry, 2013). Depending on the amount of the raw material processed, between one and 2.5 tons of red mud is produced per one turn of the alumina produced. Hence, a huge amount of red mud is produced globally each year, which is about seventy million tons. Notably, this poses an alarming and severe problem to the environment. Consequently, there is much R&D work being carried out for the utilization, storage, and disposal of red mud across the world.

Environmental Issue and, Disposal and Utilization of Red Mud

Red mud is usually disposed of as semi-dry or dries material in the abandoned bauxite mines or red mud pond and as slurry with an elevated solid concentration of between thirty to sixty percentages and having an increased ionic strength. The problems linked to the red mud waste disposal encompass its increased PH, the alkali leakage into the underground water, the safety in its storage, and air-bone alkaline dust emissions and large disposal area. About two tons of liquor having a considerable alkalinity of between 5 to 20 g 1-1 caustic come together with every one ton of the dry mud. Mainly, red mud consists of iron oxide, aluminum oxide, silicon oxide, sodium oxide, and calcium oxide among other oxides that are in trace quantity and this depends on the process parameters and mineralogy used. Regarding the particle size distribution, red mud is quite fine material. In this regard, the average size of a particle of red mud is below ten microns. A small number of particles, which are more than twenty microns are available as well. The particular SA of red mud is between ten and thirty m2/g, and this depends on bauxite grinding (Rai, et al., 2013).

Safe treating and storing of red much bring in some unique challenges related to waste management. Although red mud tends to be consolidated, it possesses a muddy consistency due to the fitness of the involved material, as well as their colloidal nature because of caustic soda found in it. Treating red mud will assist in reducing its environmental impact, and the re-utilization alternatives of red mud will come up. Attempts to improve red mud are currently being undertaken by potentially encompassing a PH-reduction step of processing. In some of these techniques, there is neutralization of caustic soda to make the red mud environmentally friendly while a technique like in sintering, red mud is combined with some materials including fly ash and what is obtained may be utilized as construction and building material. The residue sintering is performed with the intention to fix the leachable soda, and such mechanism can be employed in producing bricks from red mud.

Some studies have been undertaken in the use of red mud in the pollution control field, metal recovery, adsorbent, soil remediation, and in coagulant. Moreover, researchers have studied its application in the building and construction field. Being among the fastest expanding sectors, the construction industry is encountering a deficit of the traditional building materials because of the increasing demand for houses. In this regard, red mud can be another option to the traditional brick materials including clay, which will bring down the level of the raw material costs and also boost bulk red mud utilization. Notably, significant research has been carried out on the red mud usage as being a raw material for producing various building products. Mostly, red mud can be utilized as a building or constructional material in blocks, brick, and roofing tiles among others.

A Plan to Make Breaks from Red Mud

The plan involves making non-fired building bricks. Based on research, it has been found that red mud is treated with the HCL acid to dissolve just the sodium component and then the treated product is mixed with the kaolinitic clay to form the construction bricks (Rai, et al., 2013). Attempts have been carried out at CBRU to include a small portion of lime in the red mud. The mixture is then compressed at the optimal mixture contained in the brick form with the intention to assess their stability and strength to the water erosive action. An extreme wet compressive strength of about 4.0 MPa with five percent line, as well as 4.2 MPa having eight percent lime have gotten after four weeks of casting and the humid drying of such bricks. The ash fly and red mud were utilized in producing non-fired and non-steamed bricks by Yang in 1996 and Xing in 1993 (Yang; 1996; Xing, 1993).

Timeline

Year 2017/2018

PARTICULAR

SEP

OCT

NOV

DEC

JAN

FEB

MAR

APR

MAY

JUN

JUL

Feasibility study

Preparation

Submission

Approval of funds

Purchasing plant materials

Foundation and leveling work

Purchase order of equipment

Plant construction

Office construction

Plant and office completion

Equipment and machine arrival

HR hiring

Machine installation

Inventories purchase

Commencing production

Budget

For the project to start operating a budget covering the first one year is presented.

During the first year of the project, the fixed assets will amount 2.3 million dollars, and this will consist of the plant construction, water pipe, water tank, office equipment, office construction, and construction of the brick storage tank among others. Moreover, the inventory cost is projected to be 400, 000 dollars in the first year and this is expected to increase by ten percent every year. Finally, the workforce cost is projected to be 700,000 dollars in the first year, and this will include payments to the manager, supervisor, labor workers, and operator. The net profit at the end of the first year of operation is projected to be 2.2 million dollars.

References

Annual report, (2012). Chap V/ Department of Ministry of Mines, India 1999-2000, Retrieved from, http://mines.nic.in/archp5

Indian Aluminium Industry. (2013). Indian Primary Aluminium Market. Scribd. Retrieved from, www.scribd.com/doc/.../19149792-Indian-Aluminium-Industr

Rai, S. et al. (2013). Utilization of red mud for making bricks. Research J. Engineering and Tech. 4(1, 12-14.

Xing, G. (1993). The development of non-autoclaved brick made of red mud and fly ash. Rare Metals Cemented Carbides, 6, 154-163.

Yang, A. P. (1996). The development of brick made of red mud and fly ash. Light Metals, 12, 17-18.