Iron Control in Atmospheric Acid Laterite Leaching

Ville Miettinen,Eero Kolehmainen,Lotta Rintala,Tero Kravtsov,Jarno Mäkinen

doi:10.3390/min9070404

Ville Miettinen, Eero Kolehmainen + Show 3 more

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https://doi.org/10.3390/min9070404

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Abstract

Iron control in the atmospheric acid leaching (AL) of nickel laterite was evaluated in this study. The aim was to decrease acid consumption and iron dissolution by iron precipitation during nickel leaching. The combined acid leaching and iron precipitation process involves direct acid leaching of the limonite type of laterite followed by a simultaneous iron precipitation and nickel leaching step. Iron precipitation as jarosite is carried out by using nickel containing silicate laterite for neutralization. Acid is generated in the jarosite precipitation reaction, and it dissolves nickel and other metals like magnesium from the silicate laterite. Leaching tests were carried out using three laterite samples from the Agios Ioannis, Evia Island, and Kastoria mines in Greece. Relatively low acid consumption was achieved during the combined precipitation and acid leaching tests. The acid consumption was approximately 0.4 kg acid per kg laterite, whereas the acid consumption in direct acid leaching of the same laterite samples was approximately 0.6–0.8 kg acid per kg laterite. Iron dissolution was only 1.5–3% during the combined precipitation and acid leaching tests, whereas in direct acid leaching it was 15–30% with the Agios Ioannis and Evia Island samples and 80% with the Kastoria sample.

Highlights

Nickel is an essential element for modern industry with uses in stainless steel, nickel-based alloys, casting and alloy steels, electroplating, and rechargeable batteries [1,2]
A process involving atmospheric acid leaching of nickel laterites and simultaneous iron precipitation was investigated for the treatment of Greek LAI, LEV, and LK laterites
It was observed that iron control is possible when nickel leaching is combined with jarosite precipitation These tests involved two steps, namely, (i) acidic leaching of LAI or LEV laterite at pH 0.75 and (ii) leaching of nickel from LK laterite in higher pH with simultaneous iron precipitation as jarosite

Summary

Introduction

Nickel is an essential element for modern industry with uses in stainless steel, nickel-based alloys, casting and alloy steels, electroplating, and rechargeable batteries [1,2]. The global plant production and demand for nickel in 2015 were 1.93 Mt and 1.88 Mt, respectively [3]. A further increase in demand may be encountered due to the higher production numbers of electric vehicles (EVs) as nickel is an essential battery chemical in typical lithium ion batteries [4]. The global reserves of nickel are estimated to be 74–80 Mt including sulphide ores, laterites, and deep-sea nodules [4,5]. Even though laterites represent the vast majority of land-based reserves (approximately 72%), until 2009, less than half of the global nickel production came from nickel laterite ores. To meet the rising nickel demand in the future, it is essential to develop further the methods that allow the economic utilization of nickel laterite ores

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