Product Description:- Bentonite as a bleaching earth is a particular kind of clay derived from volcanic ash and consists mainly of montmorillonite with minor amount of illitc, kaolinite, cristobalite and other minerals. Bentonite has strong colloidal properties and, when in contact with water, increases its volume several fold by swelling, forming a tixotropic, gelatinous substance. The main characteristics of bleaching earth is its decolorizing power, that is the property of the earth to absorb selectively certain pigments rather than others according to the characteristics of the product to be decolorized (acidity, oxidation degree, origin and biological state, etc.) Bleaching earth as a filtering and decolorizing agent which is used mainly in the production of mineral oils and greases, in the production of vegetable oils and fats, fish oils and animal fats, in the regeneration of exhausted tube oils and solvent as used in dry cleaning machines.
Market Potential:- The bleaching earth requirements of the country are met through imports. The main users of bleaching earth are the edible oil mills of the country. The growth of edible oil production increases the demand for bleaching earth. Demand projection for this product can be made on the basis of projected growth of edible oil production. Demand for edible oil is projected to reach 60800 tons in 2007 and 91000 tons in 2012. About 30kgs. of bleaching earth is required to produce one ton of edible oil. This means that to produce 60800 tons of edible oil, about 1824 tons of bleaching will be required; and this will be the demand for this product by 2007. Following the projected growth for the demand of edible oil, the demand for bleaching powder will reach 2730 tons in 2012. The projected demand for bleaching powder could be sufficient to absorb, the production of a small size plant; and this plant could be established in the Amhara Region.
South of Raw material:- The main raw materials for producing bleaching earth are raw bentonite, sulphuric acid and calcium oxide. The first two raw materials can be obtained from local sources; while the east one will be imported.
Process and Technology:- The natural decoloring power of raw bentonite is very low. It can be greatly increased by an acid treatment which generates the so-called “activated earth”. The acid treatment of bentonite eliminates alkalis and calcium, reducing the contents of magnesium, iron and aluminum in it. The acid treatment can be carried out by using either sulpyhuric acid or hydrogen chloride. Calcium oxide is used for the neutralization of the spent acid. The Production process of bleaching earth from bentonite essentially involves the following operations. The crud clay is mixed with water to form a suspension to which sulphuric acid is added. The mixture is then heated by steam in a mixing tank up to a temperature of 40oC and kept at this temperature for about 4 hours. Then the mixture is heated to 1800C for one hour. After cooling the suspension is filtered through a filter press and washed in order to eliminate excess acidity. The cake of the activated earth is then dried through a pneumatic conveyor by hot air (7000C). The product is collected in a depot and then packed. The product is packed in craft paper bags of 25kgs. To avoid pollution of the final product by ordour or other impurities, natural gas or LPG is used for drying. The main machinery and equipment needed for the plant include feeding hopper, band coveyor, mixer (suspension forming), steam reactor (mixing tank), cooler, filter press, washer, drying pneumatic conveyor and storage tank.
Estimated Investment:- For a plant which can produce about 1700 tons of bleaching earth per year, the estimated investment will be:-
Buildings/shade 3300m2 at Br 1500/m2 = Birr 4,950,000
Machinery ………………………….……………. = Birr 6,360,000
Working capital ………………………………… = Birr 800,000
Total = Birr 12,110,000
Benefits:- Saves foreign exchange, utilizes domestic natural resource, introduces new skills and technology.
Location:- Any urban center near the source of raw bentonite.