Low Grade Uranium Deposits Being Exploited in China

Abstract

Known uranium deposits in China are mainly of granitic, volcanic and sedimentary types. A lot of ore deposits are low in grade and small in sizes. How to extract these resources at a profit has been a challenge to natural uranium producers. If the production cost of natural uranium from these low grade deposits is higher than the current long-term contract price in international market, a plenty of resources will be lying idle underground for a long lime. Then Chinese government's self reliance policy that the nuclear fuel of reactors will be mainly supplied from domestic natural uranium products can not be executed completely. Research works and pilot tests have been done and technical improvement have been carried out with the aim of making the low grade deposits being extracted at an appropriate profit. Effective measures have been taken by some uranium mines to reduce the production costs. Measures taken include improving the mining methods, utilizing radiometric sorting technique, extracting uranium from mine water, recovering uranium by solution mining and recovering associated useful minerals or compounds from ores. At present, some low grade uranium deposits are being exploited at proper costs. This paper will give a brief description about the improved techniques practiced and parameters achieved. Since China initiated exploration for uranium resources in 1965, a lot of uranium depos its have been found and explored in many provinces successively. Uranium deposits in China appear in a number of different types, mainly of granitic, volcanic, sandstone, carbonaceous and siliceous pelitic and uranium bearing coal seam. Considerable uranium deposits occur in intermediate and small scales. A lot of deposits are medium and low in U contents, their resources amount nearly Lo 60% of Lota] uranium. Grades of ores excavated from these depos its will be lowered to 0.08% to 0.15% in mining operation owing to dilution, thus bring on a higher production costs of natural uranium. Chinese government has decided to build nuclear power plants at certain developed area where coal is deficient. China-designed 300 MWe Qinshan Nuclear Power Station is being built at full speed this year and will be put into operation in 1990. A twin-unit (2X900 MWe) Daya Bay Station is now under construction too, and will generate electricity in 1992. A twin unit (2 X60 MWe) Qinshan nuclear power project has been approved by the government recently. New nuclear power stations have been planned to start the construction in 1990 to 2000. Chinese government decides to follow a self reliance policy that the nuclear fuel will be mainly supplied from domestic natural uranium products. The quantity of high grade known resource in China is not so plentiful to satisfy all projected reactors' life-time requirement. It is unevitable that a lot of low grade uranium deposits should be mined to meet the need. In recent years, international market price of natural uranium has stayed at a lower level, which has been a challenge to Chinese domestic natural uranium production. If domestic uranium can not be produced at a cost lower than international contract market price, then they can not compete with the imports. Coal-fired electricity has been historically the main energy in China and it's generating cost is about 0.075 yuan/kwh at present. Lower coal-fired electricity cost is a pressure for nuclear power, hence also a challenge for natural uranium production cost, although it shares only about 10% in nuclear electricity cost. Therefore taking effective measures to reduce exploitation cost of medium and low grade U deposits is very important role of Chinese natural uranium producers. Facing the serious situation, based on the geological features and exploitable conditions of deposits, appropriate measures have been successfully adopted to mine various low grade deposits at a profit. Now measures adopted in mining low grade deposits will be briefly introduced below.