Bastnaesite flotation

Effect of tall oil modifications on bastnaesite flotation from pegmatitic ores... 

Because this ore was high in barite and fluorite, direct flotation of bastnaesite from the ore was not possible. It should be pointed out that fluorite has similar flotation properties as bastnaesite and depression of fluorite during bastnaesite flotation is difficult. 

The flowsheet that was developed for beneficiation of the Dong Pao ore involves sequential barite-fluorite-bastnaesite flotation. The flowsheet is presented in Figure 24.8. 

The ground ore was first subjected to barite flotation followed by fluorite flotation. By floating the barite and fluorite ahead of the bastnaesite, about 70% of the total weight was removed from bastnaesite flotation feed. The bastnaesite flotation feed was upgraded from 8.5% REO to about 30% REO. 

During fluorite flotation, Quebracho and lignin sulphonate mixture (MESB) was used with collector composed of a mixture of oleic acid and phosphoric ester. Collectors used for bastnaesite flotation included tall oil fatty acid modified with three ethylene tetra... 

A U.S. Bureau of Mines survey covering 202 froth flotation plants in the United States showed that 198 million tons of material were treated by flotation in 1960 to recover 20 million tons of concentrates which contained approximately 1 billion in recoverable products. Most of the worlds copper, lead, zinc, molybdenum, and nickel are produced from ores that are concentrated first by flotation. In addition, flotation is commonly used for the recoveiy of fine coal and for the concentration of a wide range of mineral commodities including fluorspar, barite, glass sand, iron oxide, pyrite, manganese ore, clay, feldspar, mica, sponumene, bastnaesite, calcite, garnet, kyanite, and talc. 

From disseminated ores contained in mineral lenses, the recovery of bastnaesite and monazite is accomplished using flotation. The flotation properties of bastnaesite and monazite are similar to the gangue minerals contained in the bastnaesite and monazite, such as calcite, barite, apatite, tourmaline, pyrochlore and others, which represent difficulties in selective flotation. However, in recent years, significant progress has been made in the flotation of both monazite and bastnaesite [2,3]. 

Flotation properties of bastnaesite depend largely on the gangue composition of the ore and the impurities present in the mineral itself. Bastnaesite found in a carbonatite ore is recovered using fatty acid collector after heat pretreatment of the flotation feed. The effect of heat temperature on bastnaesite grade-recovery is illustrated in Figure 24.3. 

Floatability of bastnaesite found in barite-fluorite ores is extremely poor using either fatty acid flotation or sodium oleate. Research work conducted on an ore from Central Asia showed that the floatability of bastnaesite improved significantly after barite preflotation [5]. The flotation of bastnaesite from a carbonatite ore improved with the use of oleic acid modified with phosphate ester. The flotation of bastnaesite from deposits ofpegmatitic origin can be successfully accomplished with several types of collectors, including tall oil modified with secondary amine, and tall oil modified with petroleum sulphonate-encompassing group. 

A large portion of the REOs are produced from monazite- and bastnaesite-containing ores. In the majority of cases, bastnaesite and monazite ores are relatively complex and contain gangue minerals (calcite, barite, fluorite and apatite) with similar flotation properties as the monazite and bastnaesite. 

Flotation practice in the beneficiation of bastnaesite-containing ores... 

Flotation temperature was the subject of numerous studies. It was concluded that heating the pulp with collector is the only way to selectively float bastnaesite. Heating the pulp with collector is believed to result in selective aggregation of bastnaesite in the form of repellent droplets, which may result in improved selectivity and in a reduction in slime interference. 

The reagent scheme developed during extensive laboratory testing is presented in Table 24.7. This reagent scheme is unique in such a way that the collector and number of depressants involved are composed of a number of chemicals that provide improved selectivity during sequential flotation of barite and fluorite from bastnaesite. 

For flotation of barite, sodium silicate was used as a depressant and barium chlorite as a barite activator. Barite collector SR82 was composed of petroleum sulphonate, sodium alkyl sulphate and succinamate mixture. The collector was selective towards both fluorite and bastnaesite. Over 96% of the barite was recovered in a relatively high-grade concentrate. 

The results obtained from the continuous locked-cycle tests are summarized in Table 24.8. The major contaminant of the bastnaesite concentrate was fluorite. Complete fluorite flotation was not possible without heavy losses of bastnaesite in the fluorite concentrate. 

After comminution, mineral separation will have to take place, to separate the valuable particles from the non-valuable gangue particles. As the ore minerals of the rare earths are hardly magnetic, useful separation techniques would be gravity separation or flotation. For bastnaesite, which does not have an extremely high density, flotation is applied. The principle of flotation is depicted in Fig. 4.3. 

Bastnaesite from Mountain Pass ore (hard-rock ore) is processed as follows. After comminution, the ground ore is subjected to hot-froth flotation. However, gangue minerals like calcite, barite or celestite may cause problems in flotation, because they have flotation properties similar to bastnaesite. For this, special treatment has been devised, consisting of six different (steam) conditioning steps... 

Ores containing monazite, bastnaesite or xenotime are concentrated by ore-dressing processes, heavy medium separation or flotation. After grinding, the concentrates are converted to soluble sulfates or chlorides by digestion with acids or alkalis. 

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