Bauxite Beneficiation Electrostatic

The most widely used chemical process of refining bauxite into alumina, the Bayer process, involves dissolving the Al2O3 out of the bauxite rock with caustic soda (Naoh) at elevated temperature and pressure. The Al2O3 fraction of the bauxite is dissolved into solution, to later be precipitated out as alumina. Na izany aza, a high-grade bauxite contains up to 60% Al2O3, and many operating bauxite deposits are well below this, Tsindraindray toy ny 30-40% Al2O3. Because the desired product is a high purity Al2O3, ny oxides sisa tavela ao amin' ny bauxite (Fe2O3, SiO2, TiO2, Organic material) are separated from the Al2O3 and rejected as alumina refinery resides (ARR) or red mud. Amin' ny ankapobeny, ny kalitaon' ambany kokoa ny bauxite (ie lower Al2O3 content) the more red mud is generated per ton of alumina product. Ankoatry ny, even some Al2O3 bearing minerals, tsara kaolinite, produce un-desirable side reactions during the refining process and lead to an increase in red mud generation, ary koa ny fahaverezan' ny caustic lafo soda simika., sarany lehibe ova. ao amin' ny dingan' ny bauxite fanadiovam..

Ny forona mena na NY ARR dia maneho fanamby lehibe sy mandeha amin' ny viraty.. Ny fonon-tanana mena dia ahitana residual manan-danja residual ireo ambina simika avy amin' ny dingan' ny fanadiovam., ary alkaline fatratra, matetika amin' ny pH ny 10 - 13. It is generated in large volumes worldwide – according to the USGS, notombantombanana ho ny famokarana alumina amin' ny ankapobeny. 121 tapitrisa taonina 2016. This likely resulted in more than 150 Taonina ny fotaka mena azo nandritra ny vanim-potoana iray.. Na dia teo aza ny fikarohana tsy tapaka, Ny fotaka mena ankehitriny dia vitsy ny hitadiavam-bola ireo lalana maharikoriko mba hahazoana tombontsoa.. Izany dia notombantombanana ho fa ny fotaka mena dia azo avy amin' ny fomba ampiasaina maneran-tany.. Instead the red mud is pumped from the alumina refinery into storage impoundments or landfills, Aiza no tehirizina sy monitored amin' ny sarany lehibe..

Ny fahaverezan' ny caustic lafo soda (Naoh) and the generation of red mud are both related to the quality of the bauxite used in the refining process. Amin' ny ankapobeny, the lower the Al2O3 content of the bauxite, ny lehibe kokoa ny boky fotaka mena izay azo., as the non-Al2O3 phases are rejected as red mud. Ankoatry ny, the higher the kaolinite or reactive silica content of the bauxite, ny fotaka mena kokoa dia azo. The reactive silica content not only increases the volume of red mud, but also consumes caustic soda reagent and reduces the yield of Al2O3 recovered from the bauxite. Ary noho izany, there is both an economic and environmental argument to be made for improving the quality of bauxite prior to refining.

Ny dingan' ny fisarahana amin' ny fomba fisarahana dia manome bauxite producers na bauxite refiners fahafahana hanatanteraka ny dingan' ny Bayer upgrading bauxite akora mba hanatsarana ny kalitaon'. Izany fomba izany dia manana tombontsoa maro:

• Fampihenana ny saran' ny refinery noho ny fandaniana ambany kokoa amin' ny caustic soda amin' ny mampihena fampidirana tohina silica.
• Savings in energy during refining due to lower volume of inert oxides (Fe2O3, TiO2, Non-reactive SiO2) miditra amin' ny bauxite. Smaller mass flow of bauxite to refinery results in less energy to heat and pressurize.
• Reduction in red mud generation volume (ie – mena ny alumina mitaha) by removing reactive silica and inert oxides.
• Tighter control over input bauxite quality to refinery reduces process upsets and allows refiners to target ideal reactive silica level to maximize impurity rejection.
• Improved quality control over bauxite feed to refinery reduces process upsets, maximizes uptime and productivity.
• Reduction in red mud volume translates into less treatment and disposal costs and better utilization of existing landfills.
• Tsy misy mud mena, Ny tailings avy amin' ny dingan' ny electrostatic maina dia tsy ahitana akora simika ary tsy maneho ny fitehirizana maharitra environmental andraikitra.
• Tsy misy mud mena, dry by-products/tailings from a bauxite processing operation can be utilized in cement manufacture as there is no requirement to remove the sodium, izay detrimental ny miseho.. In fact – Bauxite is already a common raw material for Portland cement manufacturing.
• Extend operating life of existing bauxite mine by improving quarry utilization and maximizing recovery.
• STET is a low operating cost, high throughput continuous process. No water or chemicals required.