The Study On Purifying Technology Of The Medium And Low Grade Mg-B Minerals In Tibetan Key Salt Lakes

Tibetan Magnesium-Borate minerals, an important boron resources rooting in Tibetan saline lakes, is being used in domestic glass-fiber industry. The lowest grade of Boron deposit described by national standard is 3% for boron content, but the transportation is inconvenient in Tibet and the fees is fair high, and when the MgO content is beyond 17%, it will cause the grass-fiber quality poor in performance. So the grass-fiber industry demand two index to Mg-B minerals: B2O3>30,MgO<17%, so, this force the mining company to exploit those beyond 30% to make profit, thus, the lower grade wasted in vain.And that, the domestic research on the application of Mg-B minerals remain blank, but the desire to dressing technology is increasingly strong day by day. With the drying up of high grade of the minerals, mining company have to focus on the low grade minerals which was not sellable. They hope to purify the low grade minerals from 18% of B2O3 to up 30%, and decrease the MgO to 17% or even lower by simple techniques. Whereas, due to the restriction of Tibet zone, power for dressing industry is not available. This natural restriction greatly constrain the implementation of dressing technology, more rigorously, the dressing cost must be lower enough to counteract the transportation expanse, for the distance from Tibet to Qinghai is very long. So, only dressing cost must be very low that the technology is feasible. All these restriction depress the possibility nearly to zero, and by far the research beginning of this thesis, the exclusive dressing attempt concluded with failure after invested more than 1 million, for it's cost was too high.The research object in this thesis is divided into two types: the type of Nyer Co kurnakorite, and the type of Zhacang Caka-kurnakorite&pinnoite. Based on the indoor experiment, through the simple dressing procedure, screening, washing, desiccating, the comparably pure fine mineral of kurnakorite was produced, the feasibility of this kind of technology was also primarily recognized. And in mine of Niercuo, through in situ experiment, the dressing method was proved practicable. By using diesel generator, water-screening can eliminate the impurity from Nyer Co-kurnakorite minerals. Zhacang Caka - kurnakorite- pinnoite type minerals differ from Nyer Co - kurnakorite type in composition, hardness, humidity, so the processing technology need to include fragmentation and air-dressing, and the granularity should be strictly controlled to get rid of gangue.According to the research accomplishment of this thesis, several integrated dressing technology flow were concluded finally.To the type of Nyer Co kurnakorite, the technology proposed blow:Row minerals rough-screening with brine deposition pool to remove brine washing with fresh water concentration desiccating fine minerals gatheringThe detailed parameter of dressing process is:1. rough screening adopt 10mm and 1mm diameter sieve to fulfill the first round separation.2. removing brine with concentration method adopt deposition pool to achieve fine mineral 3. washing fine minerals with fresh water through 0.6mm seive4. removing water from slurry still use deposition pool5. drying up the minerals of dense slurry use press-filtering machineTo the type of Zhacang Caka - kurnakorite&pinnoite, the following process can be adopted to deal with the type of Z-9B : raw minerals(Z-9B) weathering desiccation roughly screening without water finely screening with fresh water concentrating mine slurry desiccating fine minerals gathering;The detailed operation point is:1. desiccating raw minerals before screening, for it is slightly wet and conglomerating.2. screening raw minerals to remove the gravel and other efflorescent minerals, with a sieve of 0.6mm diameter.3. the diameter of sieve for finely screening should be controlled less than 0.3mm, which is a valid diameter scale of Zhacang Caka Mg-B minerals.4. precipitating fine minerals in concentration pool, than extract liquid of the upper layer with water pump.5. desiccating the drying up the minerals of dense slurry use press-filtering machine. Adopting the proceeding technology to process the minerals can enhance the B2O3 content of Z-9B from 12% to 31% or more, and depress the MgO content under 18%.In addition, through the analysis of technical economy, less than 100 Yuan of cost for one tone of fine minerals further validate the feasibility of this technology flow. If economically using diesel oil, enlarging the production volume as much as possible, gaining profit is absolutely reachable.