INCREASING THE PRODUCTIVITY IN A MAGNESITE PILOT PLANT COMBINING OPEN BALL MILL CIRCUIT AND HIGH FREQUENCY SCREENER
AUMENTO DA PRODUTIVIDADE EM UMA PLANTA PILOTO DE MAGNESITA COMBINANDO MOINHO DE BOLAS EM CIRCUITO ABERTO E PENEIRA DE ALTA FREQUÊNCIA
Matheus Naves Moraes, Paschoal Bonadia Neto, Paulo Roberto Gomes Brandão
Abstract
Open circuit and high frequency screener have already been adopted by some mining operations, however not taking advantage of its full potential. This work presents a new approach, combining them to have a better use of the available energy and, thus, increasing productivity. This concept could fit not only the studied case but also any other ore, since it is based on the milling inner processes and the external classification. The studied magnesite process has currently four parallel ball mills operating in closed circuit with hydrocyclones, grinding the ore for the silicates flotation cells. The modification proposed changes the circuit to operate with three mills in open circuit with parameters that improves inner classification and particles transport and breakage. Their product are collected together to feed a high frequency screener, a more efficient equipment when compared to hydrocyclones. The screener oversize feeds a fourth ball mill to continue grinding and prepare the ore for the next steps, dewatering and reverse flotation. On the other hand, the screener undersize goes to desliming and reverse flotation equipment. According to the data collected in the pilot plant and the modeling for the industrial site, this modification could promote 27% increase in the productivity, due to 17.6% increase on mills feed and 7.8% in mass recovery, caused by loss reduction on desliming and flotation. The gain is expressive due to some inefficiency of the current circuit and still need to be validated on the industrial site.
Keywords
Resumo
O circuito aberto e a peneira de alta frequência vêm sendo utilizados em circuitos de moagem, mas sem aproveitar seu inteiro potencial. Este trabalho apresenta uma nova abordagem, combinando-os com o objetivo de ter um uso mais eficiente da energia disponível e, assim, aumentando a produtividade. Este conceito poderia ser aplicado não só a este minério, mas a qualquer outro, uma vez que é baseado nos processos internos da moagem e na classificação externa. O processo de magnesita estudado possui quatro moinhos de bola operando em circuito fechado com hidrociclones, moendo o minério e preparando-o para as células de flotação de silicatos. A modificação proposta altera o circuito para operar com três moinhos em circuito aberto, com parâmetros que melhoram a classificação interna e também o transporte e quebra das partículas. Seus produtos seriam coletados e juntos enviados para alimentar uma peneira de alta frequência, equipamento de classificação mais eficiente que o hidrociclone. O material retido na peneira alimentaria o quarto moinho para continuar a moagem e preparar o minério para os próximos estágios, desaguamento e então, flotação reversa. O passante da peneira, por outro lado, segue diretamente para deslamagem e flotação reversa. De acordo com os resultados obtidos na planta piloto e o modelamento do circuito industrial, esta modificação poderia aumentar a produtividade em 27%, por possibilitar o aumento na alimentação da moagem em 17.6% e aumentar a recuperação mássica do circuito em 7.8%, reduzindo as perdas na deslamagem e flotação. Estes resultados são expressivos devido a certa ineficiência do circuito atual e ainda precisam ser validados industrialmente.
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Referências
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