Different types of ores minerals chemical composition
Answers
The most commonly used iron-bearing minerals contain iron compounds as follows: hematite, Fe2O3 (70% Fe); magnetite, Fe3O4 (72.4% Fe) and of much less importance are: limonite, 2Fe2O3·3H2O (60% Fe); siderite, FeCO3 (48.3% Fe); pyrite, FeS2 (46.6% Fe) [1]. These iron percentages are in their pure states. In ores, the Fe content is lowered according to the amount of impurities present. Overall, the quality of iron ore is mainly judged based on the Fe content. More specifically, ores with Fe contents above 65% are regarded as high-grade ores; 62–64% medium- (or average) grade ores and those below 58% Fe are considered as low-grade ores [2–5].
Iron ore consumption for steelmaking was standing at 850 million tonnes at the end of the twentieth century and was estimated to reach more than 1.3 billion tonnes over the first quarter of the century [6]. The known world resources of crude iron ores are approximately 800 billion tonnes containing about 230 billion tonnes of Fe [7]. It is apparent that most of the known deposits contain low-grade ores with iron contents less than 30%. By contemporary growth of the world consumption of iron ores (about 10% per year), the known resources of iron ores could run out within the next 64 years [8]. It is thus imperative to find new sources of iron ore to supplement the existing sources, in order to meet the growing demand. Therefore, revealing and exploiting new deposits of iron ores, particularly of high-grade, is very important.
Iron ore deposits have been known to occur in the Muko area in south-western Uganda (430 km from the capital city Kampala) since the 1920s. However, they still lay unexploited and little study has been done on them. The deposits, located on six hills in Kabale/Kisoro district, occur as hematite of high Fe content. Specific quantification for the exact tonnage has not been carried out yet but estimates put the ore reserves at 50 million tonnes of raw ore.
In exploitation of any mineral, it is important to understand the main inherent properties and composition which determine their behaviour during processing. Moreover, the characteristics of minerals also often determine the economical aspect of commercial exploitation of deposits. Therefore, the main purpose of this study is to evaluate the chemical composition and microstructure of raw iron ore from Muko deposits in Uganda. The analysed chemical compositions of this ore are compared to those of major iron ore producing nations. Furthermore, it is compared with market standards in order to assess its quality and determine the viability for commercial exploitation.