Lead luster (galena) is the main type of ore from which pure lead is obtained. Extraction of metal is carried out using flotation. The origin of the mineral is associated with hydrothermal groundwater. Lead deposits are widespread throughout the world, but the oldest of them are 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 luster is an obsolete name for the galena mineral. 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 gloss is PbS (lead sulfide).
Most often, opaque galena crystals are in the form of cubes, cuboctahedrons, octahedra with blunted angles. Steps and dissolution can form on their faces. Lead-free shine with zinc blende gives leaking configurations. The kink is stepped and fragile. There are several varieties of this rock: selenium galena (selenite is present in its composition), and galena (with a dense fine-grained structure). The most common form in nature is a continuous granular mass.
The color of the mineral is steel, with a bluish tint, sometimes there is a multi-colored tint. It has a metallic sheen.
Composition
The chemical composition of the substance lead gloss includes 86.6% of 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, the mineral contains manganese, uranium, and other chemical elements. The presence of impurities is associated with microscopic inclusions of other rocks.
Chemical properties
Mineral lead gloss has the following basic chemical properties:
- in reaction with soda, a lead kinglet is formed;
- when dissolved in nitric acid, sulfur and lead sulfate are released, which precipitates as a white precipitate;
- suppression of flotation of galena is carried out by chromates and dichromates, while hydrophilic compounds of lead chromate are formed on the surface of the mineral;
- upon contact with oxygen, air quickly oxidizes, darkens, loses its metallic luster;
- During oxidation, valuable lead ores are formed: cerussite, anglesite, and pyromorphite.
physical characteristics
The main physical characteristics of lead gloss include:
- Mohs hardness - 2-3 (brittle);
- electrical conductivity is weak;
- high density - 7400-7600 kg / m 3 ;
- cleavage - ideal in cubic habit.
Origin
Deposits where lead shine 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 in the form of 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 their new types.
With natural erosive weathering and the impact of groundwater, galena forms an anglesite crust, which goes 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 change products.
Of the associated minerals, sphalerite (zinc sulfide), as well as some others, are most often found:
- pyrites;
- chalcopyrite;
- faded ores (sulfides of copper, arsenic, antimony with impurities of other elements);
- sulfosalts Ag, Pb, Cu;
- arsenic pyrite;
- quartz;
- calcite;
- carbonates;
- barite;
- fluorite.
Sometimes lead shine is found in the form of plaque on sulfuric and radiant pyrites (deposits of coal and phosphorites).
Spread
The largest galena deposits are developed in the following countries:
- USA (Ledville, Colorado);
- Russia (Sadon, Caucasus; Leninogorsk, Altai; Dalnegorsk, Primorye; Nerchinsk, 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, Altyn-Topkan (Tajikistan), Karatau, Akchagyl (Kazakhstan), Filizchay (Azerbaijan) deposits can be noted.
Artificial receipt
Lead luster can be easily obtained artificially in several ways:
- when exposed to hydrogen sulfide on a solution of lead in the presence of nitric acid;
- upon decomposition of PbSO 4 in hydrogen or carbon monoxide;
- when passing a stream of dried hydrogen sulfide gas through lead chloride compounds;
- while slowly cooling the calcined ground mixture of PbSO 4 and chalk.
Application
The main area of 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 smelting lead, galena is used in the production of whitewash, paints (meerk, crown) and glaze. Silver, bismuth, zinc and selenium are extracted from rich ores.
Lead sheen is a semiconductor. It is sometimes used in the manufacture of contact crystal detectors.
The lead content 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 shine 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. If sulfur pyrite is present in the ore, its output is suppressed using cyanide. Those ores, which 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), as a result of which the hydrophobicity of the rock surface increases.
The minerals contained in the ore, according to their ability to sulfidization, are divided into 3 groups:
- easily sulfidizable (white and yellow lead ore, lead sulfate);
- poorly sulfidizable (lead chlorophosphate);
- not amenable to sulfidization (plumboyarozit).