Potash Feldspar Beneficiation Explained
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Potash feldspar is a silicate mineral composed of potassium and aluminum. Potash feldspar is widely used in industrial sectors such as ceramic blanks, ceramic glazes, glass, electric porcelain, abrasive materials, and potash fertilizers. Its multiple usages puts higher requirements for beneficiation. This article will introduce in detail the potash feldspar beneficiation process and equipment. Let's start it!
01 Introduction of Potash FeldsparBack
Potash feldspar (K₂O·Al₂O₃·6SiO₂) belongs to the monoclinic crystal system, usually in red, yellow and white colors. Density is 2.54-2.57g/cm³, specific gravity is 2.56～2.59, hardness is 6. Its theoretical composition is SiO₂ 64.7%, Al₂O₃ 18.4%, K₂O 16.9%.
Potash feldspar is the most widely distributed and richest potassium-containing mineral. It often exists in acidic igneous rocks. Potash feldspar is often found in places with granite. In addition to orthoclase, there are two homogeneous and polymorphic variants: perlite and potassium plagioclase.
02 Potash Feldspar Beneficiation MethodsBack
In production, these potash feldspar beneficiation methods are widely adopted: ore washing, magnetic separation, flotation, acid leaching, and combined process.
(1) Ore Washing
Ore washing is suitable for potash feldspar produced from weathered granite or feldspar placer. It mainly removes impurities such as clay, fine mud, and mica, which can reduce the content of Fe₂O₃ in potash feldspar ore and increase the content of potassium and sodium. The ore washing process often uses vibrating screens or ore washing tanks. The clay, fine particles, and mica are easy to separate from the coarse-grained potassium feldspar under the action of water flow due to the small particle size or low sedimentation rate (light specific gravity).
(2) Magnetic Separation
Because the iron minerals, biotite, hornblende, and tourmaline in potash feldspar have certain magnetic properties, they can be separated from potash feldspar under the action of an external magnetic field. Generally, these kinds of minerals in potassium feldspar have weak magnetic properties, and only strong magnetic separation equipment can be used to obtain better separation results.
When potassium feldspar contains more magnetite, you should consider adopting weak magnetic separation or medium magnetic separation first, and then strong magnetic separation. This will not only avoid the clogging of the strong magnetic separator but also reduce the amount of strong magnetic minerals. It can not only avoid the blockage of the strong magnetic separator but also reduce the loss of potassium feldspar caused by the inclusion of strong magnetic minerals. A wet counter-current permanent magnet cylinder magnetic separator with sufficient magnetic recovery can be used.
In general, the iron in potash feldspar minerals mainly exists in mica, pyrite, a small amount of hematite, and iron-containing alkali metal silicates (such as garnet, tourmaline, and amphibole).
Generally, under the acidic conditions of pH 2.5-3.5, the use of amine cationic collectors can float mica. Under the acidic conditions of pH 5-6, the use of xanthate collectors can float pyrite, such as sulfide minerals. Under the acidic conditions of pH 3-4, iron-containing silicates can be floated with sulfonate collectors.
(4) Acid Leaching
When there are strict requirements for iron. Use strong acid to remove iron minerals. Use sulfuric acid as the pickling agent, blend according to the acid concentration and the iron content of the potassium feldspar fine powder. When the sulfuric acid concentration is determined, the iron content of potassium feldspar powder is proportional to the weight of added sulfuric acid. After pickling, Fe₂O₃ and Fe₃O₄ are thoroughly removed, and the ferrous sulfate solution is separated to obtain potassium feldspar powder.
03 Potash Feldspar Beneficiation EquipmentBack
The main function of the magnetic separator is to remove iron metal, and can use a permanent magnet drum type magnetic separator. The flotation machine is to remove mica in potassium feldspar, and can choose BF type flotation machine, SF type flotation machine, XCF type flotation machine, KYF flotation machine.
Dewatering stage mainly adopt thickener and filter to abotain potassium feldspar powder.
The above potash feldspar beneficiation equipment is configured according to the results of potash feldspar laboratory tests.
04 Difficulties in beneficiation of potash feldsparBack
With economic development, the demand for ceramic raw materials and finished feldspar products has increased, and the quality requirements have also increased. The mined feldspar ore is of low grade and generally co-exists with quartz, mica minerals, calcite and rutile, and must be processed to be better applied to industrial production.
The main problems are iron and silica removal.
Quartz and feldspar are often associated with each other, making it difficult to separate. This is because the physical properties, chemical composition, structural structure between the two are relatively similar. We mainly use fluorine-free flotation to separate quartz and feldspar.
Iron impurity is the main harmful element in potassium feldspar, which seriously affects its application in ceramics, glass and other fields. Some hard-to-separate potash feldspar ores not only contain high iron content, but part of the iron minerals infiltrate the potash feldspar in the form of iron staining. For these minerals, a single separation process cannot meet the requirements of concentrates. At this time, a combined magnetic separation-flotation process can be used.
05To Sum UpBack
The above is the focus of potash feldspar beneficiation. Magnetic separation to remove iron and flotation to remove silicon, and the combined process of magnetic separation and flotation to separate iron-stained ore is the most commonly used beneficiation method in potash feldspar beneficiation.
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