Glauconite-bearing rocks as alternative potassium source for fertilizer by thermal processing with additives Rochas portadoras de glauconita como fonte alternativa de potássio para fertilizantes por processamento térmico com aditivos
A carbonate-silicate low weathering phosphate ore from an igneous origin deposit in Southeastern Brazil presents a challenge mainly for apatite flotation from its gangue minerals, calcite and dolomite, plus the presence of phlogopite, diopside, magnetite, richterite, ilmenite, vermiculite, quartz and many other minor impurities. Recently, selectivity has been greatly enhanced by using CO 2 instead of air, so in this study a variant process was used. In a first stage, carbonate minerals were floated with the use of CO 2 as bubble gas; the collector was a saponified fatty acid, medium hydrocarbon chain. Then, the depressed minerals were floated using a sulfosuccinate collector and air as the froth gas. A significant improvement in the apatite concentration has been achieved: the initial 5.28% P 2 O 5 tenor was raised to 21.58%. The overall P 2 O 5 recovery was 61.8% and 12.0% of the global mass recovery. However, the amount of impurities was still significant with the presence of carbonates, phlogopite and minor magnetite. Therefore, the processing route presented herein is quite viable, but further research is necessary to improve the whole method.
Resumo Minérios fosfáticos variam muito na sua composição, e esses diferentes minérios requerem um maior número de técnicas de caracterização. Neste trabalho, o objetivo é estudar a composição de um minério fosfático e suas características eletrocinéticas, por meio de amostras de apatita e calcita. A partir das técnicas de difração e fluorescência de raios X e espectrometria no infravermelho, foi possível realizar a caracterização mineralógica das amostras, permitindo identificar as fases de apatita e calcita, e identificar os elementos presentes em cada amostra.Dados morfológicos e imagens foram obtidos a partir da técnica de microscopia eletrônica de varredura e microanálises químicas. As medidas do potencial zeta foram realizadas utilizando o nitrato de potássio como eletrólito indiferente e os pontos isoelétricosencontrados foram: pH7 para a apatita; e pH 6 para a calcita. Nas faixas de concentração do coletor estudadas, a apatita apresentou flotabilidademaior que 90% para concentração do coletor igual a 10,0mg/L, principalmente pH 9, e a calcita apresentou melhor flotabilidadenessa mesma concentração de coletor, entretanto não houve um pH que se destacasse igual no caso da apatita. Palavras-chave:Apatita;Calcita; Minério fosfático MINERALOGICAL CHARACTERIZATION, STUDY OF THE POTENTIAL ZETA AND FLOATABILITY OF APATITE AND CALCITE Abstract Phosphateoresvarya lot in composition, andthesedifferent ores requirea greaternumberofcharacterizationtechniques. In thiswork, theobjectiveistostudythecompositionof a phosphate ore and its electrokineticcharacteristics, through samples ofapatiteandcalcite. Fromthetechniquesof X-raydiffractionandfluorescence,andinfraredspectrometry, it waspossibletoperformthemineralogicalcharacterizationofthe samples, allowingtheidentificationoftheapatiteandcalcitephases, andidentifytheelementspresent in each sample. Morphological data andimageswereobtainedfromthescanningelectronmicroscopytechniqueandchemicalm icroanalysis. The zetapotentialmeasurementswereperformedusingthepotassiumnitratetheelectrolyteindi fferentandtheisoelectric pointsfoundwere: pH 7 for apatite; andpH 6 for calcite. In theconcentrationbandsstudied, apatitepresentedfloatabilitybiggerthan 90% for collectorconcentrationequalto 10,0mg/L, mainly pH 9, andcalcitealsopresentedbetterfloatabilityin thesamecollectorconcentration, howevertherewasn't pH thatstood out like in the case ofapatite.
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