Preparation of synthetic carnallite and amorphous silica from chromite beneficiation plant tailings
S. Top 1  
,   M. Yildirim 1  
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Mining Engineering Department, Cukurova University, 01330, Adana, Turkey
Gospodarka Surowcami Mineralnymi – Mineral Resources Management 2017;33(2):5–23
In this paper, synthetic carnallite (MgCl2 ∙ KCl ∙ 6H2O) and amorphous silica (SiO2) preparation possibilities were investigated by utilizing chromite beneficiation plant tailings which contain 3.44% chromite (Cr2O3) and 30.55% magnesium oxide (MgO) by weight. Firstly, laboratory scale high intensity wet magnetic separator was applied for removing the magnetic materials such as chromite, iron (II ) and manganese (II ) minerals in the tailings. About 85.75% of chromite, 91.22% of MnO and 64.71% of Fe2O3 were removed by single stage magnetic separation. After the magnetic separation, hydrometallurgical recovery was initiated by leaching of the tailings with hydrochloric acid (HCl). Amorphous silica particles and the other solids were separated from the leach solution by filtration. Impurities were precipitated from the leach solution by elevating the solution pH via magnesiumhydroxide (Mg(OH )2) adding. The purified magnesium chloride (MgCl2) solution was mixed with potassium hydroxide (KOH ) at stoichiometric ratio. According to the XRD and chemical analysis, the synthetic carnallite was synthesized by controlled heating of this solution at 90–100°C. Also, the amorphous silica with 96.5% SiO2 content and 84.38% recovery yield was obtained by additional magnetic separation treatment.
Wytwarzanie syntetycznego karnalitu i amorficznej krzemionki z odpadów wzbogacania rud chromitowych
karnalit syntetyczny, krzemionka bezpostaciowa, wzbogacanie magnetyczne, odzysk hydrometalurgiczny
W artykule przedstawiono badania możliwości wytwarzania karnalitu (MgCl2 • KCl• 6H2O) i bezpostaciowej krzemionki (SiO2) z odpadów z zakładów procesu wzbogacania chromitów, które zawierają 3,44% wag. chromitu (Cr2O3) i 30,55% wag. tlenku magnezu (MgO). W skali laboratoryjnej do usuwania materiałów magnetycznych, takich jak: chromit, żelazo (II) i minerały manganowe (II) zastosowano wzbogacanie mokre w separatorach magnetycznych o wysokiej intensywności. Około 85,75% chromitu, 91,22% MnO i 64,71% Fe2O3 usunięto metodą jednoetapowej separacji magnetycznej. Po wzbogacaniu magnetycznym odzysk hydrometalurgiczny został zainicjowany przez ługowanie odpadów kwasem chlorowodorowym (HCl). Amorficzne cząstki krzemionki i inne substancje stałe oddzielono od roztworu ługującego przez filtrację. Z roztworu ługowanego wytrąciły się zanieczyszczenia przez wzrost pH dzięki zawartemu wodorotlenkowi magnezu (Mg(OH)2). Oczyszczony roztwór chlorku magnezu (MgCl2) zmieszano z wodorotlenkiem potasu (KOH ) w stosunku stechiometrycznym. Zgodnie z XRD i analizą chemiczną, syntetyczny karnalit syntetyzowano przez kontrolowane ogrzewanie tego roztworu w temperaturze 90–100°C. Również odzysk 84,38% amorficznej krzemionki o zawartości 96,5% SiO2 uzyskano przez dodatkowe magnetyczne wzbogacanie.
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