Sulfur-containing minerals in nature is widely distributed, species are also a lot to sulfur and sulfur compounds occur in two forms, the major industrial minerals and sulfur compounds: natural sulfur, pyrite, marcasite, pyrrhotite, organic sulfur, hydrogen sulfide and sulfur in non-ferrous metal sulfide.
There are three sulfur polymorphs composite body - α S, β S and γ S. Under natural conditions, only the most stable α sulfur, called natural sulfur.
Sulfur compounds as sulfur in the ore minerals are: pyrite, marcasite, pyrrhotite, etc., of which 53.4% sulfur capacity of the most widely distributed of pyrite, sulfur is the most important ore The marcasite and pyrrhotite lower sulfur content and distribution limitations, industry has little significance.
Alunite, barite, gypsum and other sulfate minerals sulfur source only in certain countries and regions, the lack of minority to be used for sulfur mineral resources, China has not yet utilized.
(A) the nature of the main sulfide minerals
1, the natural sulfur
Natural sulfur is orthorhombic α-sulfur. Formula S, the sulfur content is 100% theory, in addition, the natural sulfur usually contain some impurities, often contain a small amount of sulfur in volcanic nature of arsenic, tellurium, selenium and titanium, often mixed with natural sulfur sedimentary calcite, clay, organic matter and bitumen and so on.
Natural sulfur is generally acicular and tabular crystals, often has irregular block output. Crystal form is rare, usually showed dense block, powder, granular, banded, and are membranous.
Natural sulfur is yellow, brown yellow, the color of impurities with red, green, gray and black. Mohs hardness of 1 to 2, accounting for 2.05 ~ 2.08; of crisp, incomplete cleavage, fracture conchoidal, with weak conductivity, heat transfer. Streak is white - yellow-white, transparent - translucent resin - adamantine luster; blue flame burns blue, and a pungent smell of sulfur. Corrosion resistance. At 360 and higher temperatures a strong effect of sulfur and oxygen to produce sulfur dioxide. At about 400 , the role of the formation of sulfur and hydrogen sulfide, the temperature continues to rise while dissociation at 1690 completely decomposed into water and sulfur. Sulfur and caustic lye and ammonia solution heated to form polysulfide or thiosulfate. Sulfur is insoluble in water, easily soluble in organic solvents and carbon disulfide. Sulfur as an oxidant and reductant appears, is chemically very active element.
Pyrite, also known as pyrite, formula FeS2, the sulfur content of 53.45% theoretical, theoretical iron content of 46.55%. Nature, often contain pyrite output of cobalt, nickel, arsenic, selenium, antimony, copper, silver and gold and other metal elements. Some also contain a very small amount of sulfide tellurium, germanium and other scattered elements.
Pyrite is isometric crystal system, common crystal shape for the cube and pentagonal dodecahedron.
Light yellow color, mostly pyrite copper, often with the surface of brown, tan, fine powder often has green black pyrite aggregates. Hardness of 6.0 to 6.5, the proportion of 4.9 to 5.2. Brittle, brown streak black or green black. Strong metallic luster, opaque, with weak conductivity. A thermal resistance, and some variants of a detector, fracture uneven, occasionally conchoidal fracture.
Marcasite (FeS2) and pyrite the same complex as the two belong to the second homogeneous body, for the orthorhombic crystal system, crystal often has plate output. Aggregates of nodule, spherical, bell emulsion, hull shape and so on.
Marcasite is light yellow copper, slightly gray or light green color, fresh face similar tin white, dark gray-green streak, metallic luster. Opacity, hardness of 5.0 to 6.0, the proportion of 4.6 to 4.9, brittle, cleavage is not complete, the fracture is irregular-shaped, with weak resistance.
Pyrrhotite [Fe1-xS] is hexagonal or monoclinic polymorphs as two variants, often has dense granular block, rare crystals, crystal was plate.
Pyrrhotite is the fresh face bronze brown, often with a dark brown surface, dark brown, opaque. Metallic luster. Gray-black streak. Hardness of 4, and crisp, the proportion of 4.58 ~ 4.70. With magnetic, but the strength varied. With conductivity, fracture is uneven to conchoidal shape.
(B) pyrite ore and associated elements of the main
1, the main benefit associated pyrite ore elements
China pyrite deposit, unless part of the sedimentary-metamorphic ore deposits in a single fraction compared to pyrite-based, the other less useful components, most deposits contain a variety of useful components. According to statistics, in the pyrite ores and oxide ores contain some useful nearly 15 species of associated components, are: copper, gold, silver, gallium, tellurium, cobalt, cadmium, germanium, thallium, manganese, sulfur benefit Comprehensive development and utilization of iron ore deposit.
2, pyrite ores of the main components and hazardous
Sulfuric acid when pyrite in the main harmful components are: arsenic, fluoride, lead, zinc, carbon, calcium, magnesium, carbonate and so on.
Arsenic: in sulfuric acid production, arsenic poisoning causes catalyst to produce arsenic oxide crystals, the conversion rate has dropped, and plug the pipe, resulting in clean-up difficult, and people are likely to poisoning; discharged wastewater containing arsenic can cause environmental pollution.
F: roasting there in most of the hydrogen fluoride, silicon tetrafluoride small part. Hydrogen fluoride catalyst can smash; make catalyst agglomeration of silicon tetrafluoride, leading to increased resistance of the catalyst, the conversion decreased. In the pickling process, the resulting hydrofluoric acid that will corrode brick lining and the ring; in the washing process, due to the solubility of fluoride, most with the sewage discharge will pollute water and affect the growth of crops.
Zinc; roasting process low melting point, easy to make baking produce scarring phenomenon.
C: content is higher, in the baking heat during the high temperature difficult to control, but also consume more oxygen, carbon monoxide or carbon dioxide affect the transformation.
Calcium and magnesium carbonate: pyrite stones in calcium and magnesium carbonate gangue (dolomite, calcite) to pyrite decomposition in the calcination process of carbon dioxide gas, diluting the concentration of sulfur dioxide gas furnace. Also, calcium and magnesium also absorb some of the sulfur dioxide to form calcium sulfate and **** to reduce the sulfur utilization, decrease the production capacity of the equipment. And the new form of calcium, **** residue in the pyrite cinder stone, the impact of utilization.
When man-made fiber in the manufacture of carbon disulfide, pyrite rock asphalt and arsenic is harmful impurities.
In the paper industry, the system can not sulfite pulp sulfur selenium, as selenium causes black paper.
In the manufacture of matches and explosives can not be contained traces of sulfur dioxide impurities, because silica would prevent burning.