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Master's portal of DonNTU
Semkovskiy Stanislav

Semkovskiy Stanislav

Faculty: Ecology and chemical technology

Speciality: Chemical technology of fuel and carbon materials

Theme of master's work:

Possibilities of improvement of composition of charges for coking in the modern terms of Donbass

Scientific adviser: Butuzova Ludmila
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Abstract on master's theme

INTRODUCTION AND ACTUALITY OF THEME

      Improvement of technology of blast-furnace production was always accompanied by toughening of requirements to the indexes of quality of metallurgical coke with the purpose of decline its expenses on production of ton of cast-iron.
      A coke, providing minimum possible expense in blast-furnace, must be characterized the followings indexes: Wr - 3-5%, Ad – 8-9%, Sdt – 0,5-1,0%, Vdaf – 0,3-0,5%; table of contents of classes > 80 mm 3-5%, < 25 mm 3-4%; М25 90%, М10 6%; CRI 20-25%, CSR 65-70% [1, 23-24].
      An index of sulphur content is one of basic indexes of quality at determination of fitness of coals for the different types of use, foremost, in the processes of semicoking and coking. Sulphureous compounds which corrode the equipment are given off at incineration of coal. Moreover, they pollute the environment. Sulphur of coke worsens its quality as a metallurgical fuel, because it turns into cast-iron in a blast furnace, giving it fragility and lowering quality of steel obtained, because of red-shortness [2, 304].
      Unfortunately the source of raw materials of Donbass is characterized with a small content of low-sulphureous coals of sorts C, F, and OC, and with coals which technical composition allows to obtain coke of the set quality. Methods of enriching and desulpharization of coal charget, as well as improvment of new technologies in the process of coking on this stage of development of industry, allows to solve this problem partly.
      Importance of problem is related to wide distribution of sulphureous coals [4, 124].

AIMS AND TASKS

      The purposes of research are the following:
  • investigation of behaviour of coals of different types on reductivity in the charge in the process of thermofiltration and in the process of semicoking;
  • improvement of composition of charge and decrease of amount of sulphur in semicoke by means of chemical pretreatment.
          The main task is to give recommendation on optimum composition of charge for provision of coke of required quality taking into account the disposed raw materials of Donbass.

    SCIENTIFIC NOVELTY AND PRACTICAL VALUE

          The problem of reductivity and composition of rational cgarge was the object of research for many scientists. Professor Ludmila Butuzova examined influence of type on reductivity on the yield of products of semicoking of separate sorts of coals [4, 124-133]. This work examines the behaviour of the different reducted coals in the shihkt in the processes of thermofiltration and semicoking.
          Practical value consists in expansion of raw materials of coking due to use of charge with middle-sulphureous and high-sulphureous coals of Donbass with the obtaining of coke, making to the requirements of blast-furnace operators.

    RESEARCHES AND DEVELOPMENT REVIEW

          In Donetsk national technical university the developments in this and other themes, related to the problem of coals reductivity are conducted under the leadership of professor Ludmila Butuzova. The problem of processing of sulphureous coals is considered in work [5]. The row of new indexes, characterizing the genetic type of coal on reductivity is exposed in the article [6]. On the world scale Russian scientists, Gulmaliev A. and Gagarin S., are engaged in this problem [7, 8].

    MAIN PLANNED RESULTS

          The objects of research are two pairs of isometamorphic coals of gases and fat of Donbass, which ere homogeneous in petrographic composition, but differentin genetic type. Description of initial coals is given in a table 1:

    Table 1 – Characteristic of initial coals.

    Mine Sort of coal Type Technical analysis, % Elemental analysis, % daf
    Wr Ad Sdt Vdaf C H O+N
    Central G, k7 LRC 2,2 5,2 1,22 36,0 85,1 5,11 8,71
    Dimitrova G, l1 RC 2,1 4,4 2,49 38,7 83,8 5,34 9,50
    Zasyadko F, l1 LRC 2,3 8,2 1,1 32,7 86,1 5,4 7,4
    Zasyadko F, k8 RC 2,2 2,6 4,1 30,5 85,4 5,2 5,3

          4 pair of charges of different combinations with correlation F : G = 70 :30 were composed. Such correlation is optimum, because the minimal quantity of wellcooking coals must be no less then 65% [9, 88].
          Researches were conducted using the method of thermofiltration in the centrifugal field with installation CPI [10, 190]. The advantage of this method constitutes in the unique possibility to separate plastic mass without beginning of the second transformations.
          By means of thermofiltration the yields of plastic mass of each sort of coals were found at the beginning. Then yields were found for 4 pairs of carge with correlation F : G = 70 : 30. The expected theoretical yield of plastic mass for the same charge was calculated taking into account the additivity using the following formula:

    s=a*w(a)+b*w(b)

    где s – yield of plastic mass;
    a, b – quantity of components of charge;
    w(a), w(b) – table of contents of this components in charge.

          The results of experimental and calculations are presented in the table 2.

    Table 2 – Yields of plastic mass for the sort of coals and charges.

    Moving-liquid products, %
    Central G, lrc Dimitrova G, rc Zasyadko F, lrc Zasyadko F, rc
    12,2962 4,7781 17,1 42
    Frc+Grc, 70/30% Frc+Glrc, 70/30% Flrc+Glrc, 70/30% Flrc+Grc, 70/30%
    calculation data experimental data calculation data experimental data calculation data experimental data calculation data experimental data
    30,83343 17,6245 33,08886 26,5243 15,65886 20,9517 13,40343 13,7767

    Dependence of yield of a calculation and experimental plastic mass is presented on a pic. 1

    Picture 1 – Comparative description of yields of calculations and experimental of plastic mass
    Frame's number – 5, replay's number – 10

          As you can see in the picture, experimental information on the yield of products of thermofiltration is not additive to theoretical ones. Yield of products and deviation in the yield of plastic mass from calculation depends on the type of reductivity and is different at identical sort of composition of charge. It testifies to chemical interaction between of components of charge. Charge containing the reducted coal of sort F and low-reducted coal of sort G. Are considered to be the optimum composition, giving the maximal yield of moving-liqued phase at the correlation indicated higher 70 : 30 mentioned above.
          Method of IR-spectroscopy with Furie's transformations (DRIFT) is used for estimation of composition and products properties of the thermal processing of charge.
          A great advantage of FT-IR method is possibility of using computer for digital accumulation and data processing. This allows to make operations of expansion and constriction of spectrums, their comparison or synthesis, factor and correlation analysis, deduction of solvent spectrum or mineral admixtures, showing and unsealing of curves, programed control of experiment and correction of basic line.
          The correction of basic line was conducted with using the computer program "Origin".
          According to the data of DRIFT-spectroscopy, the basic structural fragments of coals to be investigated are the following [12, 170]:
  • aromatic hydrocarbons;
  • aliphatic saturated Сal-Н groups;
  • -С=0 groups in saturated connections;

          The spectrums of plastic mass of two charges made from low-reducted coals of sorts F and G (pic. 2а) and the reducted coals of those sorts (pic. 2b) are shown on the picture 2. So, it is obvious, that the type of coals on reductivity determines functional composition of charge. Coals of type «RC» give the plastic layer, which differs with high content of aromatic hydrogen (V = 700-900 sm-1) and groups, which contain bridge oxygen and sulphur compounds (V = 1200-1250 sm-1).

    Picture 2 – IR-spectrums of plastic mass of charges, which are composed by low-reducted coals of sorts of F and G (pic. 2a) and reducted coals of those sorts (pic. 2b).

          For example, in the moving-liqued produced of charge Glrc + Frc relative content of СНar/СНal is sharply multiplied in relation to this index in products produced of initial coals. Nonadditively the amount of two nearly atoms of hydrogen at aromatic rings diminishes similarly. The content of bridge -О- and -S- is multiplied. These data testify to multiplying the degree of aromatic of moving-liqued, change of method of packing of aromatic rings in charge and additional formation of the three-dimensional structures sewn together at thermal treatment of coals mixture. These semiquantitative data of spectrums treatment showed that chemical interaction of components of charge takes place. It depends on the type of initial coals and determines quality of plastic layer.

    CONCLUSION AND FUTURE RESEARCH

          On this stage of master's degree work it is possible to draw followings conclusions:

    1. The yield of plastic mass of 4 pairs of charge, which were got by the thermofiltration method, are not additive to calculative yield, that testifies to chemical interaction of charge.
    2. Charge containing the reducted coal of sort F and low-reducted coal of sort G is considered to be the optimum composition, giving the maximal yield of moving-liquid phase at the correlation indicated higher 70 : 30.
    3. According to the results of IR-spectroscopy it is evidently, that the type of coals on reductivity determines the functional composition of charge and quality of plastic layer.
    4. Then these charges will be subjected to thermal destruction by semicoking method in the Fisher's retort. Composition of semicoke gas will be determined in the apparatus VTI. Semicoking resin will be parted by extraction by solvents according to the chart.

    REFERENCES

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      Электронный источник: Материалы научной конференции
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    12. Маковский Р.В., Наливкина А.О., Бутузов Г.Н. О взаимодействии компонентов шихт, составленных из углей разных типов по восстановленности // Охорона навколишнього середовища та раціональне використання природних ресурсів / Збірка доповідей VIII Міжнародної наукової конференції аспірантів і студентів. Т. 2 - Донецьк: ДонНТУ, ДонНУ, 2009, с. 170-171.

    Important note

          Master's work has not been completed to this moment yet. Final completion is December, 2009. The complete text of the work and materials on the topic can be given by the author or his scientific adviser after the given date.

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