How Nigeria can exploit untapped kaolin deposits …As RMRDC moves to stop importation
About three billion metric tonnes of kaolin is estimated to be deposited in various parts of the country; a document from the Raw Materials Research and Development Council (RMRDC) has shown.
According to the document, there have been reported large deposits of kaolin in Katsina, Plateau, Bauchi, Ogun, Ondo, Niger, Oyo, Kwara, Benue, Enugu and Ekiti states, with the Katsina deposit adjudged the best for pharmaceutical purposes because of its chemical composition.
Kaolin is a weathering product of silicate rock, the naturally occurring hydrated aluminum silicate which may be white, yellowish-white, earthy, non-porous and odourless to dull and has a plastic and slightly oily feel. It is almost tasteless and practically insoluble in water.
According to the Director General of RMRDC, Dr. Hussaini Doko Ibrahim, the annual national demand for kaolin is estimated at over 360,000 tonnes, while local production is only about 125,000 tonnes, which leaves a gap of about 235,000 tonnes.
Dr. Ibrahim said the pharmaceutical sub-sector alone had a national demand of 128.8 metric tonnes, while current supply to the sub-sector was only about 33.3 metric tonnes per annum. This indicates gross underutilisation of this natural resource locally. Uses of kaolin Dr. Ibrahim said the chemically inert nature of kaolin made it a versatile industrial mineral with wide applications in the cosmetics, pulp and paper, chalk, paints and agro allied industries and in pharmaceutical formulations.
He said, when beneficiated, kaolin could be used as a diluent in fertiliser and insecticides, and to smoothen glossy surfaces on paper, as fillers in plastics and rubber and also serve as a reinforcing agent.
Dr. Ibrahim said kaolin was also used in paint formulation and in paper filling and coating.
Medically, he said kaolin was used as adsorbent in the formulation of anti-diarrhoea preparations, adding that about 700 metric tonnes per annum of kaolin was required for the formulation of anti-diarrhoea mixtures alone in Nigeria. That is aside the quantity required for the formulation of other drugs.
In veterinary medicine, kaolin has been used as an oral antidiarrhoeal agent and as an adsorbent to treat toxin ingestion.
The DG said the bulk of kaolin in the country, which level was as high as 90 per cent, was either of sedimentary or residual origin. How to extract kaolin According to the Dr. Ibrahim, kaolin is produced by two major processing techniques: the wet and dry methods. The technique employed in beneficiating raw kaolin plays significant role in products’ end use.
In the pharmaceutical sector, where high degree of purity is required, the wet method is used. In this method, raw kaolin lumps are crushed and mixed with water to form slurry. Chemicals like diatomite may be added to decolourise the clay. The slurry is then pumped into a vibrator screen to remove all forms of impurity. The water is then separated by pumping the slurry into a filter press. The product is dried, pulverised, milled and classified. The resultant product may be processed further to improve its brightness, dispensability, electrical and water resistance properties, etc. The final product is then packaged based on specification.
In the dry process, raw kaolin is directly fed into the crusher. The crushed kaolin is milled and passed through a classifier and a blower before finally passing through a cyclone for grain size classification and storage. In Nigeria, over 90 per cent of kaolin industries use this method because it is less tedious.
RMRDC’s effort in kaolin extraction and usage
A recent survey shows that cosmetics and pharmaceutical industries in Nigeria have shown apathy for local kaolin. The inability of the locally sourced kaolin to meet the quality specification of cosmetics and pharmaceutical industries has resulted in the importation of large quantities of processed kaolin annually. To obviate this development, RMRDC initiated programmes and projects to promote industrial processing and utilisation of kaolin locally. The council established three kaolin processing plants: two plants to produce two industrial grade kaolin and one to produce pharmaceutical grade. They are located in Gwarzo and Kankara in Kano and Katsina states respectively. After the successful completion of the projects, the council divested from the industrial grade plants in line with its policy and re-invested the funds into new kaolin projects.
The council, in partnership with the Katsina State Government, established the Kankara Industrial Kaolin Processing Plant as a catalytic model factory to promote value addition and increase supply of industrial grade kaolin locally.
Initially, the pharmaceutical grade line was producing lower than capacity. As a result, a technical audit was carried out and its capacity and product quality upgraded. The council has divested its interest in the project which is now owned by the Katsina State Government.
The establishment of industrial and pharmaceutical grade kaolin plants has catalysed the establishment of similar projects by private investors. Some of these are the Integrated Minerals Limited and Kaolin and Ceramic Limited, Dutsinma, in Katsina State; Monumental Kaolin, Barkin Ladi, and ACG Mineral and Fleet Minerals in Plateau State; Jachinllins Nigeria Limited and the Bauchi Multi-Purpose Cooperative Society in Bauchi State.
The plants employ more than 1,000 people in both kaolin mining and beneficiation activities. Aside this, the RMRDC collaborated with Fleet Minerals Limited, Jos, to fabricate hammer mills and pulverisers to enhance the processing of kaolin in Bauchi State and in Umuezeana-Umunuko in Ukpor, Nnewi South Local Government Area of Anambra State.
Another major initiative of the council is to promote utilisation of standard products. This is done by ensuring quality assessment of the minerals. Towards this end, the council established Minerals Testing Centres (MTC) in Ukana, Akwa Ibom State, and in the African University of Science and Technology (AUST), Abuja. These two projects are enhancing the characterisation of industrial minerals in the country.
In an effort to promote local production of metakaolin - calcined kaolin - for use as a replacement to titanium dioxide in paint production, RMRDC developed the technology for calcined kaolin production and utilisation as a partial replacement for titanium dioxide. The council embarked on this project to produce calcined kaolin that will serve as 40 per cent partial substitute for titanium dioxide in paint making, reduce the importation of titanium dioxide by 40 per cent, develop simple indigenous technology in the processing of calcined kaolin and to stimulate interest in investment in the solid minerals sector.
The council also collaborated with Bon Affaire Industries Limited to fabricate and install a gas suspended calciner. So far, all the parts of the calciner have been fabricated and plans have also been completed to install it at the Technology Demonstration Centre (TDC) of RMRDC at the National Space Research and Development Agency (NASRDA), Lugbe, Abuja. The technology has also been patented.
Also, Dangote Cement is ready to use the calcined kaolin as extender in cement production and six investors have also shown interest in establishing similar plants in the country.
The DG said when the technology had been successfully taken over by private sector investors, it would lead to creation of more than 3,000 jobs in the up and downstream sectors of kaolin mining and processing locally.
Already, private sector investment in kaolin mining and processing is on the increase as a result of the sustained effort of organisations involved in the development of the mineral locally.
The DG assured that the council was ready to partner with both private and public sector organisations to maintain and sustain these efforts.
“Plans are ongoing to ensure the local production of most important industrial grades of calcined kaolin in order to stop their importation. Among those with high demand locally are K-white, K-white 5000 and K-white 7000 industrial grades calcined kaolin,” Dr. Ibrahim said.