Abstract
Beneficiation of manganese ores has been conducted around the world by circuits composed basically of crushing, screening and spiral classifier. Therefore, solely the coarse size fractions (and commonly the richest) are actually recovered: "lump" (-75+9mm) and "sinter feed" (-9+0.15mm). In the industrial plant which processes the ore from the Azul Mine-PA, the overflow of the spiral classifier (- 0.15mm) is disposed of in a tailings dam because it bears a low Mn content (<10%) and high kaolinite content (70%). This paper reports the findings of a process development conducted on laboratory scale with the aim of concentrating Mn-bearing minerals from the tailings of the Azul Mine-PA (7% of Mn and 70% of kaolinite). The process is composed of desliming (-10µm), followed by reverse cationic flotation of kaolinite (rougher, scavenger) at pH~5. Results indicate that the reverse cationic flotation in the acid medium, when utilizing amide amine as collector and in the presence of a silicate activator and a dispersing agent could be a possible route for the concentration of tailings that had previously been deslimed at 10µm. The results yielded a mass recovery of 18%, a metallurgical recovery of 50% and a 32% Mn concentrate which may be mixed with current high grade products, increasing the overall recovery of the plant.
Highlights
Manganese ore is a mineral resource of great prominence in Brazil, owing to the large existing reserves (53.5 million tons in 2012) and concentrated production (3.5 million de tons in 2012)
This study investigated the separation of kaolinite in the reverse flotation of the concentration of manganese tailings (Rodrigues, 2009)
Kaolinite presented a global liberation of 88%, whilst manganese oxides presented a global liberation level of 52% and an increase in the fines (Kahn et al 2011)
Summary
Manganese ore is a mineral resource of great prominence in Brazil, owing to the large existing reserves (53.5 million tons in 2012) and concentrated production (3.5 million de tons in 2012). Azul is the biggest Brazilian manganese mine and has been in operation since 1985. It is located in the north of Brazil in the Carajás mineral province and operates in synergy with other mines in the region. The manganese ore in the Azul mine is processed in a plant composed of crushers, scrubbers, screens and a spiral classifier. The coarse fractions are naturally rich in manganese, and the products from the unit are lump ore (particle size of more than 9mm) and sinter feed (size of more than 0.15mm), the fines are discarded in a tailings dam
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