Methods for preparing hematite
a technology of hematite and hematite, which is applied in the field of chemistry, can solve the problems of not being environmentally friendly, complicated, not being cost effective, etc., and achieve the effect of promoting, catalyzing and/or enhancing the formation of hemati
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example 1
Preparation of Hematite
[0112]Hematite (0.5 g) was added to a basic aqueous composition (300 mL) having a temperature of about 90° C. The basic aqueous composition contained about 17 to about 20 wt % of iron precipitate under the form of Fe(OH)2 and Fe(OH)3. The basic aqueous composition was heated over a period of time of about 5 minutes to about 20 hours under agitation at atmospheric pressure. Hematite was added over a period of time of about 5 minutes to about 20 hours at atmospheric pressure. After about 1 hour, a change of color of the precipitate is observed (from brown to red brick). The red color was intensified until a red intense color having the same color than hematite was obtained.
[0113]The above-mentioned example was carried out as a proof of concept. Then further examples have been carried out so as to carry out the precipitation of hematite from a basic aqueous that was derived from an acid leaching solution. The acid leaching solution was obtained by leaching an alu...
example 2
Preparation of Hematite from an Aluminum-Containing Ore Sample
[0114]The aluminum-containing ore (for example argillite) can be activated mechanically by grinding. Mineral activation leads to a positive influence on the leaching reaction kinetics. For example, a ball mill can be used in air atmosphere for about 2 to 4 hours. Argillite can be also calcinated. This stage of pretreatment can be accomplished at a calcinating temperature between about 400 to about 700° C. for a period about 1 to about 2 hours. These two operations, for example, increase the quantity of extracted aluminum by about 25 to 40%.
Acid Leaching
[0115]Acid leaching can be made by mixing activated argillite with an acid solution (for example HCl) at elevated temperature and under pressure during a given period of time. For example, the argillite / acid ratio can be of about of 1:3 (weight / volume), the concentration of about 6M, the pressure can be of about 70 to about 80 psi, the temperature can be of about 150 to abo...
example 3
Preparation of Hematite from an Aluminum-Containing Ore Sample Argillite
[0123]The argillite was ground up in the wet phase in a ball grinder. The mixture of water and roughly crushed argillite coming from the mine was fed into the grinder, where the mineral is reduced to less than 100 microns. The mud went down by gravity into a mixer outfitted with two impellers, which ensures a good homogeneity. When the mixture reaches the desired density, the contents of the mixer are pumped to an accumulation bunker, which will serve to feed the mud to an autoclave.
Acid
[0124]The acid fed to the leaching came from two sources. The major portion was recycled spent acid. This recycled acid contained about 20 to about 22 wt. % of hydrochloric acid (HCl) and about 10 to about 11% of AlCl3. For example, if excess acid is required, a small quantity of fresh 36% acid can be used.
Leaching
[0125]The mud of argillite and acid were fed to the autoclave of 32 m3 in stoichiometric proportion. The autoclave w...
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