Laterite standards

Schorin, H. LaBreque, J.J. (1986) Three Laterite Standard Reference materials from Venezuela. Memoirs of the Geological Survey of India 120, 89-101. 

The ammoniacal systems do not cause corrosion problems and this allows use of standard materials of construction. The process is mainly applicable to high iron limonitic laterites. The amount of acceptability of the transition ore (S-ore) is limited due to nickel loss caused by forsterite formation during the roasting process. 

In the case of mixtures, Gonzales et al. [30,31,39,40] have applied the methodology to minerals, for example, laterites [40] and zeolites [44], In Table 4.1, [44] the results of the phase analysis of several natural zeolites are reported. In Table 4.2, the elemental compositions, in oxide wt %, of the same natural zeolite rocks are reported [44], To calculate the absolute quantity of the zeolite phase in the samples used as standards, it was necessary to use the adsorption method (see Chapter 6). 

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. 

The experiment conducted at 1500 C yielded a nickel composition of 16.41% while it reached the highest value as 19.77% at 1550 C. The nickel content of the metal obtained at 1600 C was found as 15.55%. It was therefore reported that it is possible to satisfy the desired nickel composition in the metal when 25% excess coal was used at the preieduction stage. On the other hand, contrary to die experiments conducted with 50% excess coal at the prereduction, an increase in die smelting temperature from 1550 to 1600 °C caused a decrease in nickel content in the resultant alloy. The experiments performed to analyze the effects of temperature showed that production of standard ferronickel from Sivtihisar laterites is possible. It was also concluded that 1550 °C was the optimum smelting temperature for the smelting system used in the current work. 

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