Bauxite Beneficiation Electrostatic

The most widely used chemical process of refining bauxite into alumina, hawsha Bayer, 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. Si kastaba ha ahaatee, a high-grade bauxite contains up to 60% Al2O3, and many operating bauxite deposits are well below this, mararka qaar yar intii 30-40% Al2O3. Because the desired product is a high purity Al2O3, oxides haray in bauxite ah (Fe2O3, SiO2, TiO2, Organic material) are separated from the Al2O3 and rejected as alumina refinery resides (Aar oo) or red mud. Guud, tayada hoose bauxite ah (ie lower Al2O3 content) the more red mud is generated per ton of alumina product. Intaa waxaa dheer, even some Al2O3 bearing minerals, gaar ahaan kaolinite, produce un-desirable side reactions during the refining process and lead to an increase in red mud generation, iyo sidoo kale khasaaraha ka mid ah mid qaali ah kiimikada Soodhaha, kharashka variable weyn ee geedi socodka turxaan bauxite.

dhoobo Red ama Aar oo ka dhigan mid weyn iyo mid ku socda tartan loogu talagalay warshadaha aluminium ah. dhoobo Red ku jira dhamayta haraaga kiimikada hadhay weyn ka geedi socodka turxaan ah, oo waa heer sare ah xumadoodu, oo inta badan leh pH ah 10 - 13. It is generated in large volumes worldwide – according to the USGS, lagu qiyaasay saarka alumina caalamiga ahaa 121 million tons in 2016. This likely resulted in more than 150 million tons of dhoobo cas ahbaa isla muddadaas. In kasta oo cilmi-socda, dhoobo cas hadda dhowr Waddooyinkiisa ganacsi-gal ah in ay faa'iido dib-u-isticmaalka. Waxaa lagu qiyaasaa in aad u yar ee dhoobo cas beneficially waa dib-u-loo isticmaalo dunida oo dhan. Instead the red mud is pumped from the alumina refinery into storage impoundments or landfills, halkaasoo lagu kaydiyo oo lagula socdaa qiimaha weyn.

Guuldaradii ugu of Soodhaha qaali (NaOH) and the generation of red mud are both related to the quality of the bauxite used in the refining process. Guud, the lower the Al2O3 content of the bauxite, mugga weyn ee dhoobo cas in la ahbaa doonaa, as the non-Al2O3 phases are rejected as red mud. Intaa waxaa dheer, the higher the kaolinite or reactive silica content of the bauxite, dhoobada more cas loo ahbaa doonaa. 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. Sidaa darteed, there is both an economic and environmental argument to be made for improving the quality of bauxite prior to refining.

The dalab habka STET qalalan-soociddiisa bauxite saarayaasha ama dahabtumayaashii bauxite fursad ay ku qabtaan casriyeyn pre-Bayer-habka of ore bauxite si loo hagaajiyo tayada. Habkan leedahay faa'iidooyin badan:

• Dhimista in kharashka ka hawlgala warshadda sifeeynta ay sabab u tahay isticmaalka hoose ee Soodhaha by yareynta silica aqbasho Waxyeelo.
• Savings in energy during refining due to lower volume of inert oxides (Fe2O3, TiO2, Non-reactive SiO2) galaya la bauxite. Smaller mass flow of bauxite to refinery results in less energy to heat and pressurize.
• Reduction in red mud generation volume (ie – dhoobo cas ratio alumina) 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.
• Si ka duwan dhoobo cas, tailings ka habka qallalan electrostatic ku jira kiimikooyin lahayn oo aan matalin liability kaydinta deegaanka oo waqti dheer ah.
• Si ka duwan dhoobo cas, dry by-products/tailings from a bauxite processing operation can be utilized in cement manufacture as there is no requirement to remove the sodium, taasoo dhaawici soo saaridda cement. Dhab ahaan – 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.