Lead shine (galena) is the main type of ore from which pure lead is obtained. The extraction of metal is carried out by means of flotation. The origin of the mineral is associated with hydrothermal groundwater. Deposits of lead luster are distributed throughout the world, but the oldest of them have already been almost completely developed. Natural ores containing galena also contain other valuable impurities. The main scope of this mineral is non-ferrous metallurgy (lead smelting).
Description
Lead glitter is an old name for the mineral galena. This word comes from the Latin galena, which means "lead ore". The mineral belongs to the class of sulfides - sulfur compounds of metals and non-metals and is one of the most common representatives of this group. The chemical formula for lead glitter is PbS (lead sulfide).
Most often, opaque crystals of galena are in the form of cubes, cuboctahedrons, octahedrons with obtuse corners. Steps and dissolutions can form on their faces. Lead gloss with zinc blende gives sinteredconfiguration. The fracture is stepped and brittle. There are several varieties of this rock: selenium galena (it contains selenite), lead (with a dense fine-grained structure). The most common form in nature is a solid granular mass.
The color of the mineral is steel, with a bluish tint, sometimes there is a multi-colored tint. Has a metallic sheen.
Composition
The chemical composition of the lead luster substance includes 86.6% lead, the rest is sulfur. Of the impurities, the following are most often noted:
- silver;
- copper;
- cadmium;
- zinc;
- selenium;
- bismuth;
- iron;
- arsenic;
- tin;
- molybdenum.
In rare cases, manganese, uranium and other chemical elements are present in the composition of the mineral. The presence of impurities is associated with microscopic inclusions of other rocks.
Chemical properties
The lead luster mineral has the following basic chemical properties:
- reaction with soda produces a lead beetle;
- when dissolved in nitric acid, sulfur and lead sulfate are released, which precipitates as a white precipitate;
- Suppression of galena flotation is carried out by chromates and bichromates, while hydrophilic compounds of lead chromate are formed on the surface of the mineral;
- on contact with atmospheric oxygen, it quickly oxidizes, darkens, loses its metallic luster;
- when oxidized, valuable lead ores cerussite, anglesite, pyromorphite are formed.
Physical characteristics
The main physical characteristics of lead luster include:
- Mohs hardness - 2-3 (brittle);
- conductivity is weak;
- high density - 7400-7600 kg/m3;
- cleavage - ideal in cubic habit.
Origin
Deposits where lead sheen is found are characterized by two types of rock formation:
- Hydrothermal. Minerals are formed as a result of precipitation from hydrothermal solutions circulating in the bowels of the Earth. This type of deposits, to which galena deposits are confined, is the most common. It is found as veins or deposits in limestone rocks.
- Metasomatic. The appearance of ores occurs under the influence of hot mineral waters, with the simultaneous dissolution of rocks and the deposition of new types of them.
With natural erosive weathering and the impact of groundwater, an anglesite crust is formed from galena, passing deep into cerusite. These are sparingly soluble minerals that form a dense layer around the lead luster, preventing its further oxidation. Less commonly, pyromorphite, wulfenite, and crocoite are identified as alteration products.
Of the accompanying minerals, the most commonsphalerite (zinc sulfide) and some others:
- pyrite;
- chalcopyrite;
- fahlore (sulfides of copper, arsenic, antimony with impurities of other elements);
- sulfos alts Ag, Pb, Cu;
- arsenic pyrite;
- quartz;
- calcite;
- carbonates;
- barite;
- fluorite.
Sometimes lead luster is found in the form of plaque on sulfuric and radiant pyrite (coal and phosphorite deposits).
Distribution
The largest deposits of galena are mined in the following countries:
- USA (Leadville, Colorado);
- Russia (Sadonskoye, Caucasus; Leninogorskoye, Altai; Dalnegorskoye, Primorye; Nerchinskoye, Chita region);
- Australia (Broken Hill, New South Wales);
- Canada;
- Mexico.
Deposits of lead shine are found everywhere, but the oldest of them, located in Europe, are almost completely exhausted. In the CIS countries, the Altyn-Topkan (Tajikistan), Karatau, Akchagyl (Kazakhstan), Filizchayskoye (Azerbaijan) deposits can be noted.
Artificial acquisition
Lead shine can be easily obtained artificially in several ways:
- when exposed to hydrogen sulfide solution of lead in the presence of nitric acid;
- when PbSO4 decomposes in hydrogen or carbon monoxide;
- when passing a jet of dried hydrogen sulfide gas through lead chloride compounds;
- when slowly cooling the calcined crushed PbSO mixture4 andchalk.
Application
The main use of galena is a source for smelting lead. This metal is mainly used for the manufacture of the following products:
- batteries;
- sheet lead and alloys;
- ammunition;
- sheaths for electrical cables;
- technological additives for gasoline.
In addition to lead smelting, galena is used in the production of whitewash, paints (red lead, crowns) and glazes. Silver, bismuth, zinc and selenium are extracted from rich ores.
Lead shine is a semiconductor. It is sometimes used in the manufacture of contact crystal detectors.
The content of lead in ores is about 5-6%. Their enrichment is carried out using simple technologies, the choice of which depends on the size of the mineral inclusions in the rocks and the uniformity of its distribution. If the grains of lead sheen are large, then the ore is processed according to gravity-flotation schemes. First, a concentrate is obtained, which is then crushed and floated in an alkaline medium. In the presence of sulfur pyrite in the ore, its yield is suppressed with the help of cyanide. Those ores that contain a lot of oxides and sulfides (sulfide-oxidized) are enriched in two ways:
- separate flotation of sulfide and non-sulfide components;
- sulfidization of oxides followed by flotation of galena. The process consists in adding various reagents (for example, sodium sulfide), resulting in an increase in the hydrophobicity of the surfacebreed.
The minerals contained in the ore are divided into 3 groups according to their ability to sulfidization:
- easy sulfidizing (white and yellow lead ore, lead vitriol);
- poorly sulfidizing (lead chlorophosphate);
- not amenable to sulfidization (plumboyarozite).
