Abstract
Nickel laterite ore is used to produce nickel metal, predominantly to manufacture stainless steel as well as nickel sulfate, a key ingredient in the batteries that drive electric vehicles. Nickel laterite production is on the rise and surpassing conventional sulfide deposits. The efficiency of mining and processing nickel laterites is defined by their mineralogical composition. Typical profiles of nickel laterites are divided into a saprolite and a laterite horizon. Nickel is mainly concentrated and hosted in a variety of secondary oxides, hydrous Mg silicates and clay minerals like smectite or lizardite in the saprolite horizon, whereas the laterite horizon can host cobalt that could be extracted as a side product. For this case study, 40 samples from both saprolite and laterite horizons were investigated using X-ray diffraction (XRD) in combination with statistical methods such as cluster analysis. Besides the identification of the different mineral phases, the quantitative composition of the samples was also determined with the Rietveld method. Data clustering of the samples was tested and allows a fast and easy separation of the different lithologies and ore grades. Mineralogy also plays a key role during further processing of nickel laterites to nickel metal. XRD was used to monitor the mineralogy of calcine, matte and slag. The value of mineralogical monitoring for grade definition, ore sorting, and processing is explained in the paper.
Highlights
Battery manufacturing together with the demand for stainless steel is the biggest driver for the global nickel mining industry
Evaluation of the X-ray diffraction (XRD) measurements was done in several steps
A second step included minerals identification and quantification, and the results were compared to a typical nickel laterite horizon
Summary
Battery manufacturing together with the demand for stainless steel is the biggest driver for the global nickel mining industry. Since ore grades and resources of sulfide nickel deposits generally decrease, mining companies are forced to focus more on the extraction of nickel from laterites in the future, see Figure 1. Ore grades are mainly defined based on the elemental composition.3Mofin16eralogical analysis is only used for research on dedicated samples during mining and processing of nickel laterites or for the exploration of new deposits. CClluusstteerr AAnnaallyyssiiss TToo hhaannddllee llaarrggeeaammoouunnttssoof fddataataacahciheiveevdedbybryapraidpiddadtaatcaolcleocllteiocntiounsinugsinaglinaelairnedaertdeectteocrt,o“r,cl“ucslutesrtearnaanlyaslyiss”isi”sisa auusesfeuful ltotoool ltotoccoommbbiinneeddiiffffeerreenntt XXRRDD mmeeaassuurreemmeennttss ((aanndd different ore grades) into similar groups (clusters) [19,20]. Minerals 2021, 11, 1178 apply dedicated Rietveld runs on different groups of samples with different mineralogical contents, to improve the accuracy of the quantitative results. Either the correlation matrix of step 1, or the raw data is used as input, the output is again a pseudo-3-dimensional plot
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