NOVELTY - A mixture of waste oil fat (1), an alcohol (2), and an alkali catalyst (3) is transesterified. The reaction product (10) is phase-separated into light and heavy liquids (21,22). Water (11) and alcohol (12) are added to the heavy liquid, and an inorganic acid (13) is added to the adjusted solution. Mineral salt (14) is removed from the solution which is then distilled for removing alcohol (16) and water (15).    USE - For recycling waste oil fat of vegetable oils and fats, soy bean oil, rapeseed oil, sunflower oil, cottonseed oil, palm oil, sesame oil, peanut oil, camellia oil, beef tallow, lard, horse fat, fish oil, and whale oil discarded from fats-and-oils processing plants, foodstuffs manufacturing plants, restaurants, and homes, and producing high-purity glycerine used for pharmaceuticals, cosmetics, toiletries, tobacco moisturizers, solvents, printing inks, toothpastes, fragrances, explosives, anti-freezing agents, confectioneries, cellophanes, transparent soaps, fiber lubricants, cements, photographic papers, gloss appearance agents, tobacco filters, surface active agents, paints, alkyd resins, mouthwashes, soaps, and papers, and purified fatty-acid alkylester used for diesel fuels, chemical materials, industrial chemical raw materials, boiler fuels, and fuel oils.    ADVANTAGE - The method recycles waste oil fat by an easy and economical method. The viscosity of the heavy liquid is lowered, and the suspension of mineral salt produced by inorganic-acid addition is prevented. The load of glycerol purification process is decreased. Since fatty-acid alkylester of high purity is manufactured, container corrosion is prevented. Fatty-acid soap is decomposed reliably, and deterioration of glycerol is prevented. The separated mineral salt can be used as agricultural fertilizer or chemical material. The recovered water has reduced amount of impurities, and hence can be used as variable water.    DETAILED DESCRIPTION - A mixture of waste oil fat (1), an alcohol (2), and an alkali catalyst (3) is transesterified. The obtained reaction product (10) is phase-separated into light and heavy liquids (21,22), and the heavy liquid is removed. Water (11) and alcohol (12) are added to the heavy liquid for component adjustment. An inorganic acid (13) is added to the adjusted solution such that the adjusted solution has a pH of 3-7. The mineral salt (14) is removed from the adjusted solution, and the adjusted solution is distilled for removing alcohol (16) and water (15). The adjusted solution is again distilled, and the distillate is phase-separated into light and heavy liquids.    DESCRIPTION OF DRAWING(S) - The figure shows the processing block diagram of the chemical recycle method of waste oil fat. (Drawing includes non-English language text).    waste oil fat (1)    alcohol (2)    alkali catalyst (3)    reaction product (10)    water (11)    alcohol (12)    inorganic acid (13)    mineral salt (14)    water (15)    alcohol (16)    light liquid (21)    heavy liquid (22)