Beneficiation of Low Grade Manganese Ores

Manganese ores were found as small deposits scattered in many places of Indonesia such as Lampung, Jawa, West Nusatenggara, Kalimantan and Halmahera. Hight grade manganese ore with more than forty percent mangan has been exported to China and India without significant processing. The low grade one which has mangan content less than forty percent has not been exploited yet. Mangan is used mainly as an alloying element in Iron and Steel industry. About 90% of it in the form of Ferromanaganese, a ferroalloy usually containing 75% mangan. Both beneficiation plant to process the ore in to smeltable concentrate and a smelting plant to produce ferromanganese have not been available in Indonesia yet. The aim of this research is to strengthen technological capabilities in mineral processing. Especially strengthening the capability in beneficiation of low grade manganese ores. Around twenty percent mangan content in ores will be processed to become concentrate containing more than forty percent mangan The method used in this research was laboratory experiment involving “washing operation“ and flotation. For type A ore which consist of manganese powder encaps ulated by clay minerals, washing followed by gravity separation was used. It was found that concentrate containing 42% Mn can be obtained from washing a 20% Mn type A ore. Manganese lump ore, type B is physically hard consist of high silica minerals and small amount of iron. Silica was separated by Flotation process. Flotation variables used were particle sizes, frother and collector volume, and finaly pH. Pine oil as frother and xylenol as collector were kept at the same proportion. from 2, 4, 6,8 and 10 ml/kg ore. While particle sizes varies from 100, 150 and 200 mesh. pH value was adjusted in the range of 6 – 10. The adjustment was carried out by adding sodium silicate, carbonate or hydroxide. From the flotation experiments it was found that in one stage process, 8 ml/kg ore frother/collector gave the optimum results, namely 32% Mn in product stream. Tailing product cotains 15% Mn. Particle size of 100 mesh gives the best result compared to 150 and 200 mesh sizes. Prosiding Seminar Nasional Material Metalurgi, 13 Oktober 2010. Hal. 1-15