Laterite, nickel

Nevertheless, manganese nodules can, at best, be considered to be similar to land-based nickel laterites, and consequently most of the processing techniques that have been tried are similar to those used on lateritic ores. Reduction roasting followed by ammonia leaching, as in the Nicaro process, and high-temperature sulfuric acid leaching, as in the Moa Bay operation, have been extensively tried to process nodules. 

Mayze, R. Nickel laterite processing in Western Australia. Copper, Cobalt, Nickel and Zinc Recovery, Conference, Victoria Falls, Zimbabwe, July 16-18, 2001, F1-F12. 

Virnig, M. J. Mackenzie, J. M. W. Wolfe, G. A. Boley, B. D. Nickel laterite processing Recovery of nickel from ammoniacal leach liquors. Miner. Metall. Process. 2001, 18, 18-24. 

The dissolution of goethite in acidic media and the reprecipitation of the Fe as hematite, is a crucial process in the high-temperature leaching of nickel laterite ores. At 250 °C the rate of transformation increased as the Eh of the system was lowered... 

Nickel Laterite pentlandite [(Fe,Ni)9Sg] in mafic-ultramafic intrusions Steel and nonferrous alloys... 

Nickel laterite New Caledonia Shallow, water table Weathering and changing Ej -pH at the water table... 

Internal Standard Addition. An example of the use of an internal standard for phase quantification is the recent work by Madsen et in their study of the reaction mechanism of pressure acid leaching (PAL) of nickel laterite ores. This was an in situ study in which nickel laterites were reacted with sulfuric acid at elevated temperature and hydrothermal pressure to prevent the boiling of the acid. The purpose of pressure acid leaching is to dissolve any nickel-bearing phases into the acid and subsequently treat this with solvent extraction for the recovery of the nickel. There has been much ex situ work done to the reaction mechanisms of this system, but these studies have relied on the cooling of the system prior to any analytical work. 

Figure 11.5 Results of quantitative phase analysis during pressure acid leaching of saprolitic nickel laterite ore.

I. C. Madsen, N. V. Y. Scarlett and B. I. Whittington, Pressure acid leaching of nickel laterite ores an in-situ diffraction study of the mechanism and rate of reaction, J. Appl. Crystallogr., 2005, 38, 927-933. 

B. I. Whittington, J. A. Johnson, L. P. Quan, R. G. McDonald and D. M. Muir, Pressure acid leaching of arid-region nickel laterite ore part II. Effect of ore type. Hydrometallurgy, 2003, 70, 47-62. 

Ca(UO2)2(Si03)2(OH)2. uranophane Nickel Laterite NOX acid, bese Precipitation Oxidized salts... 

Table 9.2-2 summarizes the various methods used for the treatment of direct leaching ores. Typical minerals are listed, and those that can be leached by nonoxidative dissolution (NOX) are indicated, lliose requiring oxidants (OX) are also indicated. In some cases pretreatment is required, as in the case of reduction roasting of nickel laterites or vanadium ore which may be subjected to an oxidative salt roast prior to nonoxidative dissolution. Also indicated in Table 9.2-2 are the typical lixiviants used in the process, die methods used for metal recovery, and the form of the final product produced. 

Nickel Laterite (FeNi)0(OH) nH20t limonitic RR-OX or Precipitation NK), metallic... 

Nickel Laterite Processing Technologies - Where To Next , Jim Kyle, ALTA 2010, Perth, Western Australia. 

Developments and Trends in Hydrometallurgical Processing of Nickel Laterites, Boyd Willis, ALTA 2012, Perth, Western Australia. 

ACID LEACHING OF NICKEL LATERITES WITH JAROSITE PRECIPITATION... 

Keywords Nickel Laterite, Atmospheric Leaching, Jarosite Precipitation, Pressure Acid... 

Alkali addition for iron precipitation, associated with sulfuric acid leaching of nickel laterites, has been considered periodically since the late 1960s, shortly after the development of the jarosite process for iron control in zinc refining. 

By its nature this topic is somewhat of a summary of the development of nickel laterite acid leaching with jarosite and alunite precipitation, as iron and to some extent aluminum are significant acid consumers and can be problematic for downstream metal recovery. 

Development of the Jarosite process in the zinc industry in the 1960s led to an understanding that iron could be precipitated from nickel laterite atmospheric leach solutions, at moderate acid levels, by the addition of an alkali such as potassium, sodium, or ammonia, whilst maintaining a temperature in excess of 90°C [4]. 

Work in the late 1960s led to a number of patents being issued concerning the sulfuric acid leaching of nickel laterites with addition of an alkali to precipitate iron [5, 6, 7]. The abstract of one of the patents summarizes the process intent well ... 

Researchers at the National Technical University of Athens published a number of papers in the 1980s and early 1990s, where jarosite precipitation of iron from nickel laterite acid leach solutions was considered [9, 10, 11, 12]. 

AMAX researchers added an alkali to nickel laterite PAL slurry, primarily to improve settling properties [13], However it was noted that iron and aluminum precipitation occurs ... 

Australian Nickel Laterite Pressure Acid Leaching Operations... 

In the late 1990s, the Cawse and Bulong nickel laterite PAL operations utilized saline waters, resulting in similar chemistry to that of the AMAX alkali addition work. The Murrin Murrin operation subsequently added ammonium sulfate to achieve a similar result. A number of laboratory studies by the CSIRO identified that the precipitation products are mixed alunite-jarosite compounds, with the iron progressively converting fi-om jarosite to hematite as the leach progresses [15, 16]. 

In the 1990s, BHP Minerals developed a number of hydrometallurgical technologies with the potential to improve on perceived shortcomings with PAL, to support development of the Gag Island nickel laterite project. The aims included being ... 

Whilst BHP Billiton developed a range of technologies in the area of nickel laterite acid leaching, two technologies stand out in the area of atmospheric leaching with jarosite precipitation. These are ... 

Figure 2. Idealized Cross Section through a Nickel Laterite Profile [25]...

Calcium in the form of calcium carbonate contained in limestone is added in the neutralization processes after nickel laterite leaching. Calcium sulfate solids in the form of gypsum (and possibly hemihydrate and anhydrite) precipitate and have the potential to form scale on equipment and piping surfaces. 

Jarosite containing nickel laterite leach residues are chemically stable if kept in contact with alkali (sodium) containing liquors. Jarosite breakdown remains manageable, even in the absence of the stabilizing alkali ions, particularly where excess acid neutralizing reagent has been added, as occurs when processing via the mixed hydroxide process route. 

J.A. Johnson, etal. Process Water Salinity Effects in the Pressure Acid Leaching of Cawse Nickel Laterite Ore, Chloride Metallurgy 2002, E. Peek, G. Van Weert, Eds., CIM, Montreal, Quebec, Canada, vol. 1, 2002, 339-354. 

J.A. Johnson, B.I. Whittington, Effect of Ammonium, Sodium and Potassium Sulphates and Chlorides in Pressure Acid Leaching of Western Australian Nickel Laterite Ore, Pressure Hydrometallurgy, M.J. Collins, V.G. Papangelakis, Eds, CIM, Montreal, Canada, 2004, 199-214. 

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