Peat, formation, properties, types, production and application

Peat, formation, properties, types, production and application.



 

 

Peat is a fossil, sedimentary, friable rock, a fossil fuel, formed during the decay of plants in the marshland.

 

Description, composition and characteristics of peat

The formation of peat

Physical properties of peat

Classification of peat. Types, subtypes, groups and types of peat. Equestrian, transitional and lowland peat.

Peat extraction

Use and application of peat

 


Description, composition and characteristics of peat:

Peat is a fossil, sedimentary, friable rock, a fossil fuel, formed during the decay of plants in the marshland.

Peat looks like a loose, earthy mass, gray, yellow, brown, brown, brown-black or black. In the Botanical composition of the peat are the remains of wood, bark and roots of trees and shrubs, different parts of herbaceous plants, as well as sypnowich and sphagnum mosses.

Peat is a renewable mineral resource and renewable energy source.

The peat lies on the surface or at a depth of several tens of meters under the cover of mineral deposits.

Peat is intermediate between soil formation (soil) and brown coal. From the first it differs by the presence of organic compounds – more than 50% of dry substance, and from second to high moisture content and poorly decomposed organic residues of plants, and the presence of cellulose, carbohydrates. Under the influence of high pressure and high temperature at great depths in the bowels of the earth, the peat turns into brown coal.

Peat from the chemical point of view, is a complex mixture of mineral and organic components. The content of mineral components should be it is not more than 50% in terms of dry substance. The presence of mineral components and their quantity determine the ash content of the peat. Everything else is organic decomposition products of plants, structureless (amorphous) organic matter (compost, humus). In its natural state peat contains 86-95% water.

The degree of decomposition of peat ranges from 1 to 70 %. Depending on the degree of peat decomposition distinguish the poorly decomposed peat (20 %), sredneslozhivsheysya (20-35 %) and silnoroslye (over 35 %). The maximum value of the degree of decomposition is found in wood and wood-grass peat group, the minimum from the moss.

Peat the ash content is classified into low-ash (< 5 %), crenately (5,1-10 %) and high ash (> 10 %). The high ash content typical for the lowland type, the lowest for peat.

Chemical composition and properties of peat depend directly on the type, Botanical composition and decomposition degree. The composition of peat is composed of the following chemical elements: carbon – 48-65 % of the organic matter (the Organic part of peat that the dry matter, excluding ashes), oxygen – 25-45 %, hydrogen – 4,7-7 %, nitrogen of 0.6 to 3.8 %, sulfur – up to 1,2 % (in rare cases – up to 2.5 %), calcium – up to 5 % and silicon oxide – to 43 % by weight of ash, calcium oxide, up to 40 %, aluminium oxide – up to 12 %, iron oxide – up to 13%. There are also trace elements: zinc – 250 mg/kg, copper – 0,2-85 mg/kg, cobalt is 0.1 – 10 mg/kg, molybdenum, and 0.1-10 mg/kg, manganese – 2-1000 mg/kg. In the component composition of the organic matter content of peat bitumen (benzene compounds) is 1.2-17 %, water soluble and hydrolyzable substances from 10-60 %, of cellulose, 2-10 %, humic acid – 10-50 %, lignin (neytralizuya residue) – 3-20 %.

Chemical composition of peat, has attained the utmost degree of decomposition (70 %), is characterized by minimum content of cellulose, soluble and hydrolyzable substances. In that peat is nearly exhausted energy material for biochemical processes.

The world’s peat resources are enormous and according to various estimates range from 250 to 500 billion tons. It covers about 3% of the land area. Thus in the Northern hemisphere peat more than in the South. Storvannet grows when moving to the North.

 

The formation of peat:

Peat is formed in a swampy area, in the so-called peat bogs occurring in the river valleys (floodplains and terraces) and in the watersheds. Plantsthat grow on the moor (trees, shrubs, grass, mosses, lichens, etc.) over the years, wilt, descended to the bottom of swamps, where due to high humidity and lack of oxygen is not completely decomposed, and under the influence of biochemical processes evolved into an organic, unstructured (amorphous) matter – peat. Decomposition and biochemical processes occurred and are occurring mainly in the warmer period of the year, at lower groundwater levels. Thus, the peat has an organic (biogenic) origin. The theory of biogenic origin of peat, coal and oil were proposed by M. V. Lomonosov.

The process of thoracoplasty does not end, but happens all the time. The average rate of formation and accumulation of peat is different and depends on the prevailing source of plant groups, geographical and climatic zonality, the hydrologic and other conditions, and varies from 0.2-0.4 mm (the swamp forest) to 1 mm (coniferous-broadleaved subzone) per year. Modern peat deposits formed in 10 000 – 12 000 years.

 

Physical properties of peat:

Parameter name: Value:
The density of peat, kg/m3 (dependent on moisture content, degree of decomposition, ash content, composition of mineral and organic parts) from 800-1080 (in vivo) to 1400-1700 (dry)
Specific heat of combustion, MJ/m3 (increases with increasing degree of decomposition and content of bitumen) 10-25
Moisture content, kg/kg (depending on Botanical composition and decomposition degree) from 6.4 to 30
Porosity, % 96-97
The filtration coefficient, m/s (minimum values at the peat type high decomposition degree, a maximum of the peat low-lying type.) 0.1•10-5 4.3•10-5
Ash content, %:
peat low-lying type from 6 to 18
peat transitional type 4 to 6
the peat type 2 to 4
The thermal conductivity (depends on the humidity of peat. The lowest thermal conductivity of dry peat, the largest – in wet) low

 

Classification of peat. Types, subtypes, groups and types of peat. Equestrian, transitional and lowland peat:

Under the terms of thoracoplasty according to the degree of mineralization of water supply there are three types of peat:

riding type of peat – the peat formed of vegetation oligotrophic type, in the Botanical composition of which not more than 10% of residues eutrophic type. It is poorly decomposed peat in which there are intense physical-chemical transformations. Has a high acidity ph of 2.5-3.2. Characteristic fibrous structure and low content of mineral elements;


transition type peat – the peat formed of vegetation oligotrophic and eutrophic types, in the Botanical composition of which more than 10% of residues of these types. Located between upland and lowland. A fully physico-chemical processes, it is not yet over, so it has a slightly acid reaction with ph of 3.2 to 4.2. It is characterized by the presence of a sufficient number of different minerals;

low-lying type peat – the peat formed of vegetation eutrophic type in the Botanical composition of which is not more than 10% of residues oligotrophic type. This is completely decomposed peat has a neutral reaction ph of 4.2 to 5.5.

Each peat type by the ratio of the main plants of the peat-forming plants in their requirement for abundant water supply is divided into subtypes:

forest, in the Botanical composition of which wood residues from 40 to 100%,

– the forest-mire – from 15 to 35%,

– mire – no more than 10%.

The ratio in the peat residues of certain groups of plants of the peat-forming plants in each peat type are the following groups of peat:

– wood in the Botanical composition of which wood residues from 40 to 100 %,

– woody-herbal – wood residues from 15 to 35 %, grass 35 to 85 %,

– woody-moss – wood residues from 15 to 35 %, moss from 35 to 65 %,

– grass – wood residues not more than 10 %, herbaceous from 65 to 100 %,

– grass-moss – wood residues not more than 10 %, grass 35 to 65 %, moss from 35 to 65 %,

– moss – wood residues not more than 10%; moss from 70 to 100 %.

Continuous combination of the prevailing residues of certain types of plantsof the peat-forming plants, reflecting the original plant Association groups are divided into types.

Pine peat – peat wood group, in the Botanical composition is from 40 to 100 % of residues of pine and shrubs.

Pine-cotton-grass-peat – peat woody-herbal groups, in the Botanical composition is from 35 to 85 % of the residues of cotton grass, and from 15 to 35% pine.

Pine-sphagnum peat moss – peat moss wood-moss group, in the Botanical composition is from 35 to 65 % remnants of sphagnum mosses and from 15 to 35% pine.

Cotton grass peat moss – peat moss grass group in the Botanical composition is from 40 to 100 % of the residues of cotton, not more than 35 % peat moss and 15% pine.

Saharawi peat moss – peat moss grass group in the Botanical composition is from 40 to 100 % of residues scheuchzer, not more than 35% of hollow sphagnum mosses and no more than 15% pine.

Cotton grass-sphagnum peat moss – peat moss grass-moss group, in the Botanical composition is from 35 to 65 % of residues with a predominance of herbaceous cotton, 35 to 65 % of sphagnum moss and not more than 15 % pine.

Saharawi-sphagnum peat moss – peat moss grass and moss groups in the Botanical composition is from 35 to 65 % of residues herbaceous dominated scheuchzer, 35 to 65 % of sphagnum moss and not more than 15 % pine.

Magellanicum-peat – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of sphagnum mosses with a predominance of sphagnum-magellanicum and not more than 10 % hollow mosses.

Fuscum-peat – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of sphagnum mosses with a predominance of sphagnum-fuscum and not more than 10 % hollow mosses.

Integrated peat moss – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of sphagnum moss, of which more than 15% of hollow sphagnum mosses together with the remnants of hollow herbaceous plants.

Sphagnum hollow peat – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of sphagnum moss, of which more than 50% of hollow sphagnum mosses together with the remnants of hollow herbaceous plants.

Wood transitional peat transitional peat wood group, in the Botanical composition is from 40 to 85 % of the residues of birch and pine.

Wood transitional sedge peat transitional peat woody-herbal groups, in the Botanical composition is from 35 to 65 % of the residues of sedges and 15 to 35 % of wood.

Woody-sphagnum transition peat transitional peat woody-moss group, in the Botanical composition is from 35 to 65 % remnants of sphagnum mosses and from 15 to 35% of wood.

Transitional sedge peat transitional peat herbal group, in the Botanical composition of which more than 65 % of the residues of sedges, not more than 30% mosses and 15% wood.

Saharawi transitional peat – peat transition herbal group, in the Botanical composition of which more than 65 % of the residues scheuchzer with a mixture of sedges, not more than 30% mosses and 15% wood.

Sedge-sphagnum transitional peat – transitional peat, grass-moss group, in the Botanical composition is from 35 to 65 % remnants of sphagnum moss, 30 % sedges with an admixture of scheuchzer and not more than 15 % of the wood.

Gipsovy transitional peat transitional peat moss group, in the Botanical composition is from 70 to 100 % of the residues of mosses, of which more than 30 % gipsovyj and not more than 15 % of the wood.

Transitional sphagnum peat transitional peat moss group, in the Botanical composition is from 70 to 100 % of the residues of mosses, of which more than 30% sphagnum and 15% wood.

Alder peat – peat wood group, in the Botanical composition is from 40 to 100 % of the wood residues, which are dominated by the remains of the bark and alder wood.

Pine peat – peat wood group, in the Botanical composition is from 40 to 100 % of the wood residues, which are dominated by the remains of pine wood.

Willow peat – peat wood group, in the Botanical composition is from 40 to 100 % of the wood residues, which are dominated by the remains of the bark and wood of willow.

Birch peat – peat wood group, in the Botanical composition is from 40 to 100 % of the wood residues, which are dominated by the remains of the bark and wood of birch.

Spruce peat – peat wood group, in the Botanical composition is from 40 to 100 % of the wood residues, which are dominated by the remains of the bark and wood of spruce.

Woody-sedge peat – peat woody-herbal groups, in the Botanical composition is from 35 to 65 % of residues herbaceous, sedges of which more than 35 %, and from 15 to 35% of wood.

The wood-reed peat – peat woody-herbal groups, in the Botanical composition is from 35 to 65% of the herbaceous residues, of which more than 35 % of the residues of cane, and from 15 to 35% of wood.

Wood gipsovy peat – peat woody-moss group, in the Botanical composition is from 35 to 65 % of the residues of mosses, of which more than 35 % sypnowich, and from 15 to 35% of wood.

Wood-sphagnum peat – peat woody-moss group, in the Botanical composition is from 35 to 65 % of the residues of mosses, among which more than 35 % sphagnum, and from 15 to 35% of wood.

Homely peat – peat lowland grass group in the Botanical composition is from 35 to 65% of the herbaceous residues, among which more than 35% horsetail, and no more than 15% of the wood.

Reed peat – peat lowland grass group in the Botanical composition is from 35 to 65% of the herbaceous residues, among which more than 35% of the cane, and not more than 15 % of the wood.

Reed-sedge peat – peat herbal group, in the Botanical part of which among the remnant is dominated by herbaceous sedges and reeds, no more than 35% mosses and 15% wood.

Rotational peat – peat herbal group, in the Botanical part of which among the remnant is dominated by grassy a watch, no more than 35% mosses and 15% wood.

Sedge peat – peat lowland grass group in the Botanical composition of the herbaceous residues, among which is dominated by sedges, not more than 35% mosses and 15% wood.

Saharawi peat – peat lowland grass group in the Botanical composition of the herbaceous residues, among which is dominated by scheuchzer, not more than 35% mosses and 15% wood.

Sedge-gipsovy peat – peat grass-moss group, in the Botanical composition is from 40 to 65 % of residues gipsovyj mosses from 40 to 65 % of the sedges and 15% wood.

Sedge-sphagnum peat – peat grass-moss group, in the Botanical composition is from 40 to 65 % remnants of sphagnum mosses from 40 to 65 % of the sedges and 15% wood.

Gipsovy peat – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of mosses, which are dominated by hypnosia and not more than 15 % of the wood.

Sphagnum peat – peat moss group, in the Botanical composition is from 70 to 100 % of the residues of mosses dominated by sphagnum, and not more than 15 % of the wood.

 

Peat extraction:

Peat extraction is carried out in an open way, because all peat deposits are located on the earth’s surface. There are two basic schemes of peat extraction: relatively thin layers from the surface of the earth and deep pits to the full depth of the peat layer. The first of these schemes, peat is extracted, cutting the top layer, according to the second excavator (or lump) method.

 

Use and application turf:

Peat unlike other minerals , has complex application. It is used as fuel, as a fertilizer, as the insulating material as a raw material in chemical industry, environmental and other purposes.

Peat-containing soils serve as a natural filter for natural water.

Peat has a restorative function. It restores poor, depleted, contaminated and eroded soils. Effectively absorbs heavy metals, nitrates and other impurities and substances. Reduces the effect of pesticides.

The most widely peat and its processing products (humates, humic acid, etc.) used in agricultural production. In agriculture it is used as a source of replenishment of humus in the soil to improve its water, physical and biological properties. Peat contains all the necessary plant nutrients in easily digestible plants forms. It improves soil porosity, increases its acidity. It has antiseptic properties, inhibiting the development of pathogenic microflora.

Peat burns well, highlighting the comparison with other fuels, a small amount of heat. Thus, to obtain the same amount of thermal energy requires a different amount of fuel, which in first approximation may take the following relationship:

1 ton of coal = 2.3 t milled peat = 1.6 tons of lump peat;

1 ton of oil = 4, 4 MT of milled peat = 3.0 MT of lump peat;

1000 m3 of natural gas = 3.7 MT of milled peat = 2.5 t lump peat.

However, it must be borne in mind that the peat contains oxygen, which allows it to burn without an additional supply of air. Because of this feature, peat fires occur, peat deposits, which are difficult (almost impossible) to extinguish.

The use of peat as fuel is minimal. The share of peat in energy balance of Russia is less than 1%.

Peat is a valuable chemical raw material. It produces hundreds of chemicals.

 

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