High Fluoride Beryllium Ore Smelting Process

The beryllium plays an important role in many branches of engineering, especially in the aircraft industry, for its outstanding physical properties. With the decreasing of beryl ore, one of the best quality beryllium minerals, much attention has been payed in the research on extracting beryllium oxide from the beryllium minerals containing large amounts of fluorine.The sulphate process has been used to treat beryl ore in 6th SMELTERY OF SHUIKOUSHAN for many years. However, when the beryllium minerals contain a large amount of fluorine, the pretreatment should be employed and resulted in lower grade and recovery of beryllium . In this thesis, Be(OH)2 precipitation, instead of ore pretreatment was investigated and a new flowsheet based on sulphate process has been proposed. Compared with the ore pretreatment, the new flowsheet has some advantages, such as higher grade and recovery, lower cost.In the process of evaporation-neutralization-crystallization, it was found that most of the impurities (iron, aluminum) in the concentrated leach liquor could be separated from beryllium, when the solution was adjusted to pH1.5 with ammonia gas and cooled to room temperature for crystallization, because of aluminum and iron forming ammonium alum and ferrous ammonium sulphate with the (NH4)2SO4 in the solution. Research on precipitation conditions showed that 50-70% fluorine still remained in the waste liquor and can be separated from beryllium when the F/BeO of the solution was 20-40%, and the amount of fluorine in the precipitate was about 12%. It is known that the process is greatly depended on the precipitating temperature and precipitant's concentration, with less relation to the ratio of F/BeO of the neutralized solution. The waste liquor treatmentshowed that the loss of BeO could be reduced to 1.5%, when the waste liquor was under good conditions, including temperature, concentration of fluorine and ammonium sulphate and pH of the waste liquor.Research of the recovery of beryllium oxide from the ores containing a large amount of fluorine by the new flowsheet showed that the quality of BeO could meet the standard of GB3135-82, the recovery of BeO could reach 75.17%, and the cost for 1000Kg BeO was about Y7000 lower than that with the ores pretreatment process.Fluorine and aluminum removing behavior and their effects on BeO recovery have been also discussed. It was found that the concentration of fluorine in the neutralized solution has a great influence on the separation of aluminum and should be controlled in a narrow range. It was deduced that a high recovery of BeO was able to be obtained by reducing the concentration of both fluorine and (NH4)2SO4.