Boksit Beneficiation Elektwostatik

Pwosesis chimik ki pi lajman itilize nan raffinage Boksit nan alumina, pwosesis Bayer la, enplike nan Al2O3 soti nan woch la Boksit ak soda rilan (Naoh) nan tanperati ki wo ak presyon. The Al2O3 fraction of the bauxite is dissolved into a solution, which is later precipitated out as alumina. Sepandan, high-grade bauxite contains up to 60% Al2O3, and many operating bauxite deposits are well below this, occasionally as low as 30-40% Al2O3. Because the desired product is a high-purity Al2O3, the remaining oxides in the bauxite (Fe2O3, Sio2, TiO2, Organic material) are separated from the Al2O3 and rejected as alumina refinery resides (ARR) or red mud. In general, the lower the quality of the bauxite (sa vle di, lower Al2O3 content), the more red mud is generated per ton of alumina product. epi tou, even some Al2O3-bearing minerals, notably kaolinite, produce undesirable side reactions during the refining process and lead to an increase in red mud generation, as well as a loss of expensive caustic soda chemical, a high variable cost in the bauxite refining process.

Red mud, or ARR, represents a large and on-going challenge for the aluminum industry. Red mud contains significant residual caustic chemical leftover from the refining process and is highly alkaline, often with a pH of 10 - 13. It is generated in large volumes worldwide – according to the USGS, estimated global alumina production was 121 million tons in 2016. This likely resulted in more than 150 million tons of red mud generated during the same period. Despite ongoing research, red mud currently has few commercially viable paths to beneficial re-use. It is estimated that very little red mud is beneficially re-used worldwide. Olye de sa, the red mud is pumped from the alumina refinery into storage impoundments or landfills, where it is stored and monitored at a high cost.

The loss of expensive caustic soda (Naoh) ak jenerasyon an nan labou wouj yo tou de ki gen rapo ak bon jan kalite a nan Boksit yo itilize nan pwosesis la raffinage. In general, pi ba a Al2O3 kontni nan Boksit la, pi gwo volim labou wouj ki pral pwodwi, kom faz ki pa Al2O3 yo rejte kom labou wouj. epi tou, pi wo a kaolinite oswa reyaktif silica kontni nan Boksit la, yo pral pwodwi plis labou wouj. 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. Se poutet sa, both an economic and environmental argument must be made to improve the quality of bauxite prior to refining.

The STET dry separation process offers bauxite producers or bauxite refiners an opportunity to perform pre-bayer-process upgrading of bauxite ore to improve the quality. This approach has many benefits:

• Reduction in operating cost of refinery due to lower consumption of caustic soda by reducing input reactive silica.
• Savings in energy during refining are due to the lower volume of inert oxides (Fe2O3, TiO2, Non-reactive SiO2) entering with bauxite. A smaller mass flow of bauxite to the refinery results in less energy to heat and pressurize.
• Reduction in red mud generation volume (sa vle di, red mud to alumina ratio) by removing reactive silica and inert oxides.
• Tighter control over input bauxite quality to the refinery reduces process upsets and allows refiners to target ideal reactive silica levels to maximize impurity rejection.
• Improved quality control over bauxite feed to the refinery reduces process upsets and maximizes uptime and productivity.
• Reduction in red mud volume translates into less treatment and disposal costs and better utilization of existing landfills.
• Unlike red mud, tailings from a dry electrostatic process contain no chemicals and do not represent a long-term environmental storage liability.
• Unlike red mud, dry by-products/tailings from a bauxite beneficiation operation can be utilized in cement manufacture as there is no requirement to remove the sodium, which is detrimental to cement manufacture. In fact, bauxite is already a common raw material used in Portland cement manufacturing.
• Extend the operating life of existing bauxite mines by improving quarry utilization and maximizing recovery through effective bauxite beneficiation.
• STET is a low operating cost, debi segonde pwosesis kontinyel. No water or chemicals are required.