is considered as a potential alternative to partial compaction, briquetting, thermal preparation of coal charges;

) allows to save the traditional method of layer coking, which is a significant factor, regarding the current state of Ukraine's economy;

does not require much maintenance and capital costs.

1 Relevance of the topic

Many countries of advanced coking industry, such as Germany, Japan, the USA, etc, develop new approaches to preparation of coal charges with various additives of chemicals. However, now it is difficult to implement the large-scale use of caking additives, for the reasons as follows:

The mechanism of interaction between caking additives and organic unmined coal is understudied;

There are scientifically grounded criteria for choice of caking additives;

There is no accredited method to estimate effectiveness of caking additive;

The influence of caking additives on coal of various metamorphic grade varies [3] ] and depends on their ratio in coal charges, complicating therefore the result prediction [4-6] .

Considering the raw material source base of Ukraine, i.e. the lack of strongly coaking coal and prevalence of sulphur coal inadequate for charring, the development of resource-saving methods for low quality fuel processing by adding organic additives is essential.

2 Purpose and tasks of research

The main purpose of investigation is to examine the features of co-pyrolysis of unconventional charges’ components with sulphur coal on semi coking and coking stages.

Tasks are as follows:

Investigation of organic additives influence on output and composition of solid, liquid and gaseous products;

Detection of possibilities to control the processes of unconventional charges’ thermal destruction by introduction of additives;

Adjust the output and components of semi charring and charring products increasing the output of solid residue and liquid non-volatile products.

3 Scientific novelty and practical value

The use of non-traditional charges with a big content of low-caking coals with high sulfur content requires the development of special methods of coal preparation, which include the method of adding organic additives to the charge mixture.

In this paper we for the first time studied the effect of organic additives on the processes of semi-coking and coking of coal charges from differently deoxidized coals.

Based on the results obtained we developed the conditions of pyrolysis of low-quality coals and additives. We have shown the possibility of expanding the domestic resource base of coking by increasing the share of low-caking components aiming to rationally use the coals of Donbass, recycle the plastics and harmful products of their destruction.

4 Objects of research

As the basic objects of research were used isometamorphic pairs of caking and noncaking Donetsk coals the same stages of meta¬morphism of different genetic types by reductivity: reduced (RC) and low-reduced (LRC). The characteristic of researched coals is shown in the Table 1. Samples of RC and LRC coals were selected from the closely-spaced coal seams in the same mine.

Table 1 – Characteristic of initial coal

Coal			Elemental analysis, % daf			Technical analysis, %
mine	sort of coal	type	C	H	O+N	Wa	Aa	Vdaf	Sdt
Central	k7,G	LRC	85,1	5,11	8,71	1,75	4,4	36,0	1,22
Zasyadko	k8,J	RC	85,4	5,2	5,3	0,66	2,7	30,5	4,1

From the two given coals we composed the two-component charge with previously optimized ratio of components G_LRC+J_RC = 50/50% [7] , in which we introduced the following organic additives (3–5 %):

acrylic acid dinitrile (AAD):

expanded polystyrene (EPS):

coal-tar pitch (CTP):

5 Methods of research

In the given research we used the following methods:

semicoking;

technical and elemental analysis of the study of coal;

quantitative analysis of semi-coking gas;

identification of semi-coking product yield;

coking in the apparatus of Sapozhnikov;

elemental analysis and technical analysis of solid products of pyrolysis;

6 Results of research

The results obtained during laboratory semi-coking of coal charges with additives are given in Table 2.

Table 2 – Yield of products semicoking, % daf

The charge, a brand of coal, the percentage of components		Yield of products semicoking
		Semicoke	resin	Pirogenetic water	Semicoke gaz
Initial charge	GLRC+JRC 50/50	75,28	9,79	3,57	9,29
Charge with additives	GLRC+JRC 50/50 +3%EPS	75,16	11,21	4,98	8,65
	GLRC+JRC 50/50 + 5% EPS	73,35	13,22	4,96	8,47
	GLRC+JRC 50/50 + 5% AAD	80,51	6,97	4,77	7,75
	GLRC+JRC 50/50 + 5% CTP	78,76	7,22	5,39	8,63

With the introduction of 3% of AAD in the coal charge the yield increases – from 75,28 % in the initial charge (without AAD) to 80,51 % with the addition of a charge, and the yield of liquid and gaseous products decreases. Consequently, this additive intensifies the processes of radical polymerization in the solid phase.

Additive of 5 % of CTP increases the yield of semi-coke up to 78,76 % and of the pyrogenetic water to 5,39 % due to a sharp decrease of the output of semi-coke gas yield to 8,63% and 7,22 % of the resin, which may indicate an intensification of the polycondensation reactions in the solid phase.

Additives of 3-5% of EPS alter the semi-coking product yield in the opposite direction relative to the original charge. In this case, we observe the decrease in the output of natural semi-coke and semi-coke gas and the max output of the semi-coking resin(13,22%), which may indicate an increase in the caking ability of coal charges.

According to the results of quantitative analysis of semi-coke gases (Fig. 1) we can make the following conclusions:

the introduction of organic additives leads to a decrease in the yield of СО₂, heavy hydrocarbons C_nH_m and simultaneously increase the yield СО and Н₂;

the use of expanded polystyrene and coal-tar pitch are an increase of CH₄;

semi-coke gas derived from coal charge with the addition of expanded polystyrene and coal-tar pitch in the amount of 5%, is the most high-calorie fuel, since it is enriched with features such as СО, H₂ and CH₄, which provides a higher heat of combustion.

Figure 1 – Quantitative analysis of semi-coke gas

From the results of elemental and technical analysis of solid products of pyrolysis (table 3), we can say that the use of additives reduced the amount of sulfur with 2,01 in the starting material up to 1,6–1,5 in the semi-cokes and up to 1,38–1,32 – in the coke. Using the AAD minimizes the amount of sulfur contained in the coke, to 1,32 %. In addition, the use of additives leads to an increase in carbon content and lower hydrogen content in the coke. Thus, the organic additives contribute to a more complete processes of thermal degradation.

Table 3 – Elemental and technical analysis of solid products of pyrolysis

Coke from charges	Сdaf	Hdaf	Wa	Ad	Vdaf	Sdt
GLRC+JRC,50:50	95,77	2,56	3,0	4,6	5,0	2,01
GLRC+JRC,50:50 + 3 % EP	95,85	2,36	4,3	4,6	4,6	1,67
GLRC+JRC,50:50 + 5 % EP	96,53	1,55	3,5	4,8	2,0	1,48
GLRC+JRC,50:50 + 5 % AAD	95,77	1,96	3,2	5,1	2,1	1,32
GLRC+JRC,50:50 + 5 % CTP	96,55	1,70	2,1	4,7	1,61	1,38

Conclusion

For implementing the integrated rational processing of low-quality fuels the method of semi-coking of unconventional coal charges with the use of organic additives seems to be quite suitable. It allows us to:

expand the coking resource base by increasing low-caking components of coal charges;

manage the processes of thermal degradation of coal charges, namely the process of redistribution of hydrogen in the direction of increasing the yield of solid residue and liquid products of semi-coking;

to regulate the yield and composition of semi-coking products;

solve the problem of the disposal of plastic waste and hazardous products of their destruction, which are environmentally hazardous materials.