Use of Mineral Coal for Sorption Sewage Treatment
A.V.Mozolkova Ruian University of People’s Friendship.Moscow, Ruia E.V.Chekushina Ruian University of People’s Friendship.Moscow, Ruia A.A.Kaminskaya Ruian University of People’s Friendship.Moscow, Ruia
Treatment of mining, industrial, household and other sewage is an actual problem for many mining and proceing enterprises.Coal-mining industry is not an exception.Usually, at coal enterprises, treatment of mine sewage before it is dumped consists in settling and subsequent filtering.Many pollutants are not removed from the sewage by this method.Hence, dumped water frequently does not satisfy sanitary requirements regarding the permiible content of oil products, diolved substances and other parameters.
For additional cleaning of sewage it is poible to use sorption methods.By these methods water is cleaned of oil products, heavy metals, a number of organic substances and other polluting substances, depending on the used sorbent properties.Both natural and artificial materials can be used as sorbents.Constraint for wide use of sorption methods of sewage treatment in the coal industry is high cost of the majority of sorbents.
A number of technologies for obtaining inexpensive and good quality sorbents from coal minerals have been developed.These sorbents can be manufactured directly in coal mines which has additional advantage of reducing transport costs.The procees sorbents may be recycled or burnt.Apart from that production and sale of sorbents can serve the coal-mining enterprises as an additional source of income.
One of the most widespread sorbents is activated coal.Quality activated coals are carbon sorbents, having an internal specific surface of more than 500㎡/g, and characterized by iodine adsorption (iodine value) of more than500mg/g.mineral coal, peat and wood can serve as raw materials for activated coal production.Traditional production techniques of activated coal include two basic stages of thermal proceing of the initial carbon-containing raw material-carbonization and activation, done in different devices.Both stages are energy-consuming and ecologically dangerous, which explains the high cost of activated coal, received through this technology (1200-4000 dollars/MT).
Carbonization is the elimination of volatile substances by heating up to the temperature of 600-900℃, because with volatile components there are basically formed the oxygen and hydrogen, and increase carbon content in initial raw material.Carbonization is done in mining or rotating furnaces with utilization of external form-holder, as a rule, waste gases with temperatures of 600℃ and higher.
Activation means increasing the volume and pore surfaces of carbonized material at heterogeneous reaction.The most used reagent is water vapour with the temperature of 900℃ and higher, and the proce takes 15-20 hours.
Both stages are energy consuming and pose threat to environment.For one tonne of activated coal from 2 up to 4 tonnes of specific fuel like crude oil and natural gas are consumed.From 1000 up to 1500 m³ of proceed gaes with high content of SOx (1-2 g/ m³), H2S (200-250mg/ m³), resinous substances (10-40mg/ m³), phenols (50-70mg/ m³), carbon oxides (up to 5%) and also other substances which are carcinogenic and mutagenic are formed and released into the atmosphere during both stages.High-energy consumption and environmental danger, which requires large investments in nature protection activities, result in the high cost of quality-activated coal.
Another group of carbon sorbents, which was widespread in the 80’s, consists of inexpensive carbon sorbents used in nature protection technologies and industry.Such sorbents are produced by a one-phase technology, without additional activation.Their adsorption activity is not high (iodine value le than 300mg/g) but the cost is low (250-700 USD/MT).because the price of these sorbents is comparable to the cost of their regeneration, they are used only once and are burnt after saturation.The leaders in the production of such sorbents are Rheinbraun AG (Germany, 200 thousand MT per year) and Australian Char Ltd (Australia, 150 thousand MT per year), which produce brown coal semi-coke used for treatment of wastewater and smoke.In Ruia research work in this direction is conducted, but only test works have been done so far, although the quality of carbon sorbents obtained from Kansk-Achinsk coals did not concede to production from Rheinbraun AG and Australian Char.One of the directions of utilization of semi-coke from Kansk-Achinsk coals, production of which was planed at Krasnoyarsc thermal power station 2 (device ETX-175), was its utilization as carbon sorbent.
The reason for production of inexpensive carbon sorbents by one-phase technologies being not developed in Ruia is the absence of demand for this product.This production is basically used for cleaning of sewage, however there is no effective ecological service in Ruia, and the penal sanctions of the environmental protection legislation are so insignificant that industrial enterprises do not have ant motivation to invest in nature protection.In1992-1994 the employees from Joint-Stock Company “Carbonica-F” (at that time Open Company “Sibtermo”) have developed a new method of production of carbon sorbents, which considerably from all known technologies.During the research of dynamic effects in a layer evaporator the regime conditions were defined under which the effect of “thermal wave” could be observed in the device.Using this effect, the authors created a layer evaporator in which volatile components of coal were exposed to gasification (incomplete oxidation), and the degree of carbon conversion was adjusted by the mode of injection feed.By changing the regime parameters it was poible to conduct the proce as fuel gasification (with only ashes remaining in the end) without any residue, and also as gasification of volatile components of coal, thus receiving so-called semi-coke containing solid coal.From one tonne of Kansk-Achinsk coal with calorific content of 3600-3800 kcal/kg can be produced about 0.33 tonnes of semi-coke with calorific content up to 7000 kcal/kg (as anthracite) and up to 1700 m3 of combustible gas with calorific content of 800-900 kcalJm3, suitable for use as an energy source.Technological proce of Joint-Stock Company \"Carbonika-F\" has a large number of advantages in comparison to the already known methods of obtaining activated coal and semi-coke
1.Simplicity of hardware.One-phase proce.The stages of drying, pyrolysis, thermal decomposition of volatile substances and semi-coke cooling are incorporated in one device.The device is auto- metric; it means that external heat-carrier for coal heating is not used.
2.Ecological safety.In the technology of Joint-Stock Company \"Carbonica-F\" all hydrocarbons, including resinous substances, are broken down and gasified inside the device during the formation of combustible gas containing only CO, H2, CO2, N2, H20, H2S and insignificant quantity CH4.Sludge, pyroligneous waters, phenols and other harmful impurities are not formed in this proce.
3.Because the speed of gas filtration from a layer reactor is low (0,02-0,03 m/s in comparison to 0,5-2,5 m/s for mine furnaces), the proce is le dependent on fractional composition of coal, hydraulic resistance of the layer and allows to proce fine-grained coals.
4.As a result of low speed of filtration the phenomenon of carrying out of fly ashes from the layer does not occur, because the device works as a granular filter.Combustible gas is moved in user-boiler or can move to the gas turbine without preliminary cleaning.The volume of SOx, NOx, CO contained in waste gases is lower than that produced when obtaining equivalent quantity of heat by burning coal.Combustible gas without prior cleaning can be used to produce electric and/or thermal power or as an energy carrier for thermal procees.5.Unlike the already existing technologies, in the given proce there is no dump（排空孔） of gaseous heat-carrier(气体热载体) into the atmosphere and consequently（因此） the construction of other additional gas purification systems（更多的天然气净化系统工程） and catalytic burning of carbon oxide (CO)（催化燃烧的碳氧化物） is not required.与现有的技术不同，在以上给出的过程呢个中，没有气体热载体排放的到空中的排空孔，因此，更多的天然气净化系统和催化燃烧的碳氧化物的工程是不必要的。
Test of the solid residue (semi-coke) have revealed, that this material is characterized by large specific surface (more than 500㎡/g) and high adsorption activity (iodine value 500mg/g and higher), and because of these parameter does not concede to quality-activated coal.
经过试验的固体残渣（半焦）表明：这种材料的特点是表面积大（大于五百平方米）并且有很强的吸附性（碘值是500毫克每克甚至更高）而且因为这些参数并不退让与高质量的活性炭。
The product received with the technology of Joint-Stock Company \"Carbonica-F\" is certificated as activated coal ABG (active, brown coal of gasification), for it there were developed technical conditions TU 6-00209591-443-95.The characteristics of ABG activated coal produced from the coal of 62 mark from \"Berezovsky-1\" opencast colliery.获得技术联合股份公司\"Carbonica-F认证的产品被认证为ABG类活性炭（就是具有活性的棕色的气化煤）为此，在此基础上又发展了TU 6-00209591-443-95技术条件。ABG活性炭的特点来自于出产它的来自\"Berezovsky-1\"露天煤矿的62号煤。
High specific surface and adsorption activity of ABG coal is explained by the fact that both gasification of coal volatile components, and activation of carbon-containing solid residue of gaseous products occur in the device simultaneously.Because gasification products contain up to 20%n of hydrogen whose molecules are smaller than the ones of water vapour, and hence their permeability in pores of semi-coke is higher, activation (heterogeneous reaction) is done not only with vapor, but also with hydrogen, which practically is not present in the traditional technologies.Thus, carbonization stages and activation are combined in one device.气化煤挥发性成分和激活含碳固体残留气体产品同时在装置上发生的事实就解释了ABG煤的高比表面积和强大的吸附特性。因为气化产品包含了20%以上的氢，而这些氢分子比那些水蒸汽要小一些，因此他们在半焦气孔的渗透率就高一些，激活（异构反应）就完成了，不仅与蒸汽，还与氢，而这些实际上是传统技术中不存在的。因此，碳化阶段和激活是在同一装置中同步进行的（相结合的）。
Other positive effect of application of this method of coal proceing is that in \"thermal wave\" mode the products of thermal decomposition which contain very toxic resinous substances (coal tar pitch used in experimental medicine for the inoculation of cancer in experiments on mice, brown coal is more toxic), paing through a hot layer of semi-coke (500-700℃) are completely broken down into two and three-nuclei gases H2O, CO2, CO, H2.Measurements done at the working production plant of Joint-Stock Company \"Carbonica-F\" have shown that the gas does not contain hydrocarbons of lines above methane, and also carcinogens, including benzo (a) pirene.其他应用到这种方法的积极效果是在“热波”模式中产品的热分解含有剧毒物质的树脂（煤沥青用于实验医学的接种癌症的实验小鼠，褐色碳毒性更强。）经过一个半焦的热层（500到700摄氏度）完全分解成双核或三核气体：水，二氧化碳，一氧化碳，氢气。测量工作在\"Carbonica-F\"联合股份公司的工作生产厂完成，这表明了这种气体不仅包含了碳氢化合物甲烷以上的行，也包含了致癌物质，包括：
Cooling of the activated coal from 550 up to 70℃ before discharging is carried out by compulsory circulation of gaseous heat-carrier (waste gases) through a layer of the product and further through shell-and-tube heat exchanger in which water used in closed circuit is also provided.Total proce efficiency reaches 95% due to the high degree of utilization, which is aociated with utilizing the thermal energy.在把活性炭从高于550摄氏度冷却到70摄氏度的过程以前，
Departing waste gases do not undergo any cleaning; there are even no cyclones.Neverthele, the content of harmful mixtures (NOx 150 mg/m3, SOx 50 mg/m3, ash le than 10 mg/m3) is eentially lower than the established norms and parameters of working boiler and thermal power stations, even those equipped with modern multistage systems of gas purification including electro filters.This is explained by a insignificant ablation of ash from devices, sorption of sulfur compounds in activated corner, and also focus temperature from the user-boiler is lower than 1600℃- “threshold（” 阈值） temperature at which begins the formation of nitrogen oxides due to the oxidation of nitrogen from the air.汽车尾气不经过任何清理，也没有分离器。然而，有害混合物的含量（NOx 150 mg/m3, SOx 50 mg/m3,含灰尘少于10 mg/m3)实质上比规定和工作锅炉和热电站的参数都要低。甚至是那些配备了现代化多级系统的气体净化过滤器。这是用来自仪器燃烧产生的毫无意义的灰尘来解释的，硫磺混合物的吸附作用在激活的一角进行，并且也把用户锅炉法制温度低于1600℃作为重点，而这个温度是空气中的氧化氮形成氮氧化物的开始。
The technology of Joint-Stock Company \"Carbonica-F\" can be used for any not conglomerating coals.\"Carbonica-F\"联合股份公司的技术可以被用在任意的非聚合煤上。
Similar sorbents or slightly conceding in quality to activated coal are formed by semi-coking of unconglomerated coal.Semi-coke received by using the technology developed and patented at Joint-Stock Company \"Carbonika-F\" is characterised by large specific surface (above 500 m2/g) and high adsorption activity (iodine value 500 mglg and more), and with these parameters does not concede in quality to activated coal.The production of this sorbent is ecologically safe.The producon by-product-combustible gas can be burnt in boilers of thermal power station.类似的吸附剂或是质量稍微差一点的活性炭油由聚合碳的半焦形成。半焦被使用该技术发展和专利的\"Carbonika-F\"联合股份公司使用，特点是表面积大（大于500平方米/ g），和高吸附活性（碘值500 mglg等）而且这些参数不会影响到活性炭的质量。生产这些吸附剂是具有生态安全性的。产品的副产品会在热电站的锅炉里被燃烧。
Some mineral coals (called mesoporous) have internal pores acceible to water, having the size 3.5-4 manometers (mesopores), forming active surface, sized 50-120 m2/g (unlike all other natural coals with surface of 0.5-1 m2/g).These coals can be used as sorbents without additional activation.They clear water of undiolved and diolved mineral oil, deep dispersing mixtures, iron, phenol, ions of heavy metals, ammonia, nitrates, benzo(a)pirene and so forth.Sorbent MIU-S received from poorly metamorphosed mesopore coal can be used for 3-7 years with periodic regeneration.Alkali regeneration solution is removed from the fitter without other additional neutralization, because in alkali and acid medium MIU-S presents buffer properties, neutralizing these media.一些矿产煤（叫做孔）有内部吸水孔，面积在50-120 m2/g（不像其他自然界的煤表面积是0.5-1 m2/g）。这些煤无需激活就可以被用作吸附剂。他们可以清理不溶水和融化的矿物油，深层分散混合物，铁，酚，重金属离子，氨，硝酸盐，苯等等。MIU-S吸附剂来自劣质变形孔煤，可以在定期更改新的情况下用3-7年。碱再生解决方案从管工上移除而没有其他而外的失效，因为酸和碱的中介MIU-S存在缓冲性能，能够中和这些媒介。
Specific porous structure of mesopore coals aures sorption extraction of diolved mineral oil products with concentration lower than 1 mg/l, and thus is not always reachable even with activated coals.具有特殊渗透结构的孔酶能够吸附提取溶解浓度低于1毫克/升的矿物油产品，因此并非总是能获得活性炭。
Using MIU-S filters in drinking water supply systems made the stability of their work in conditions of continuous exploitation evident, maintaining the properties of sorbents at null and sub-zero temperatures and absence of bioma formation.使用MIU-S filters在饮水供应系统中使用MIU-S filters可以使系统工作具有稳定性。可以为储蓄开采创造条件，保证吸附剂在零度或是零下温度条件下都可以持续进行且没有生物的形成。
Besides the abovementioned technologies, sorbents can be obtained from material coal by its briquetting and activation.Raw mineral for briquettes can be coals of any rank.除了上述提到的技术，吸附剂可以从矿物煤中通过成型和活化获得。制作煤球的矿物原料可以是任何一种煤。 Thus , sorbents suitable for additional cleaning of sewage are poible to be produced from mineral coals by special proceing, and sometimes directly.Production of own sorbents may solve the problem of additional cleaning of sewage in coal enterprises.Mesopore coals can be used as sorbents without additional proceing; the other coals need additional activation.The studied sorbents can be used for cleaning sewage water from mineral oil products, organic substances and metal ions.因此，适合附加清洗下水道里的)污物的吸附剂可以通过特殊处理从矿物煤中得到，并且有时候是可以直接得到的，不需要特殊处理。制作自己的吸附剂可以解决煤炭企业附加清洗污水的问题。有孔煤不经过额外的处理就可以直接被用作吸附剂；其他的煤需要额外的处理才行。吸附剂的研究能被用于矿物油产品，有机物质和金属离子的污水处理中。
REFERENCES Kovaleva LB., Matvienko N.G., Solovyeva E.A., Tarnopolskaya M.G.: The Application of Natural Mineral Coal in the Technology of Sewage Treatment from Mineral Oil.World n Mining Ecology.Works of the Congre 1999, pg.310-315.2.Congre o For the preparation of the article have been used materials from the site www.carbonica.scn.ru, www.miu-sorb.ru
