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We supply metallurgiacal coke. The subgroups of metallurgical coke are blast furnace coke, foundry coke, and other industrial coke.

FOUNDRY COKE

Foundry coke is a solid-fuel product containing about 80 per cent of carbon produced by distillation of coal to drive off its volatile constituents: used as a fuel and in metallurgy as a reducing agent for converting metal oxides into metals. The product is consumed by foundries which recycle scrap steel to make cast and ductile iron. Major markets include automotive, agricultural, and pipe foundries. Foundry coke, which accounts for 5 to 7 percent of annual metallurgical coke production, is used primarily in the production of cast iron in cupola furnaces, both as a fuel and as a source of carbon for the melted product.

  

Table 1. Quality Specifications for Foundry Coke

 Parameter   Result
 FC, %  87
 Size, mm  60 min
 Ash, %  9,5 - 15
 Moisture, %  3,5 
 S, %  1,6 
 P, %  0,35

BLAST FURNACE COKE

Coke is the most important raw material fed into the blast furnace in terms of its effect on blast furnace operation and hot metal quality. A high quality coke should be able to support a smooth descent of the blast furnace burden with as little degradation as possible while providing the lowest amount of impurities, highest thermal energy, highest metal reduction, and optimum permeability for the flow of gaseous and molten products. Introduction of high quality coke to a blast furnace will result in lower coke rate, higher productivity and lower hot metal cost.

A good quality coke is generally made from carbonization of good quality coking coals. Coking coals are defined as those coals that on carbonization pass through softening, swelling, and resolidification to coke. One important consideration in selecting a coal blend is that it should not exert a high coke oven wall pressure and should contract sufficiently to allow the coke to be pushed from the oven. The properties of coke and coke oven pushing performance are influenced by following coal quality and battery operating variables: rank of coal, petrographic, chemical and rheologic characteristics of coal, particle size, moisture content, bulk density, weathering of coal, coking temperature and coking rate, soaking time, quenching practice, and coke handling. Coke quality variability is low if all these factors are controlled. Coke producers use widely differing coals and employ many procedures to enhance the quality of the coke and to enhance the coke oven productivity and battery life.

Table 2. Coke Quality Specifications for Blast-furnace coke

Property 

Test Method 

Standard: TU U  322-00190443-114-96

25 - 60 mm

25 mm and up

KD 

KD1 

KD2 

KD3 

 Ash content,%, max

 GOST 11022

 12,0

 11,0

 12,0

 13,0

 Mass fraction of total sulfur,%, max

 GOST 8606 or GOST 4339

 2,0 

 2,0

 1,6 

 1,3

 Mass fraction of total moisture,%, max

 GOST 27588

 5,0

 5,0

 5,0

 5,0

 The strength index:  M25, min

 DSTU 2506

 86,0

 86,0

 84,0

  82,0

 Mass fraction of pieces of a size of, %, max

    GOST 5954.1

   

 over 80 mm

 -

11,0 

 15,0 

20.0 

 over 60 mm

  20,0

-

 -

 over 25 mm

 4,0

 3,5

 4,0

4,5 

The coal-to-coke transformation takes place as follows: The heat is transferred from the heated brick walls into the coal charge. From about 375°C to 475°C, the coal decomposes to form plastic layers near each wall. At about 475°C to 600°C, there is a marked evolution of tar, and aromatic hydrocarbon compounds, followed by resolidification of the plastic mass into semi-coke. At 600°C to 1100°C, the coke stabilization phase begins. This is characterized by contraction of coke mass, structural development of coke and final hydrogen evolution. During the plastic stage, the plastic layers move from each wall towards the center of the oven trapping the liberated gas and creating in gas pressure build up which is transferred to the heating wall. Once, the plastic layers have met at the center of the oven, the entire mass has been carbonized. The incandescent coke mass is pushed from the oven and is wet or dry quenched prior to its shipment to the blast furnace.

NUT COKE 

Operation of many blast furnaces has demonstrated the possibility of coke saving and increase in productivity when using nut coke mixed with the burden, but the reasons for this phenomenon, and consequently the limit for nut coke consumption, are still not very clear. It was supposed that the decrease in coke consumption while using nut coke is caused by the higher reactivity of nut coke compared with the BF coke and that the nut coke reacts preferably with carbon dioxide and in this way ‘protects’ the charged BF coke from the solution loss reaction in the shaft.

However investigations both in the laboratory under simulating solution loss reaction conditions and in industrial blast furnace using nut coke in the ore burden by adding ZrO2 tracer to the coal blend have not proved this theory.

The charging of nut coke in blast furnace is associated with reduction in coke rate and increase in the BF productivity. The replacement ratio of nut coke with BF coke is 1 i.e. nut coke replaces BF coke by equal amounts. The reasons for this replacement are:
• Feeding nut coke mixed with iron bearing materials into blast furnace results into improvement of gas permeability in ‘dry zone’ of the blast furnace. Calculations of gas permeability when mixing nut coke in the sinter layer showed that mixing of 10 volume % of nut coke in the sinter layer resulted in a decrease in the pressure drop in the dry shaft by 5.33 %. With the drop in pressure the gas flow rate increases. This in turn means increased blast volume and increased blast furnace productivity. BF productivity increases by 1.5 % to 2.5 % when using 10 to 20 weight percent of nut coke to BF coke rate. 
• Improvement in the reduction conditions of the iron burden. Due to the nut coke charging along with the ore burden, direct reduction is promoted in the cohesive zone and inhibited in the hearth zone. This also improves the hearth heating.
• The isothermal reduction in absence of nut coke in the ore burden shows retardation at the elevated temperature due to the formation of liquid slag which blocks the pores of the sinter pieces and inhibits further diffusion of the reducing gas. Mixing nut coke in the sinter burden improves the sinter reducibility through improvement in the gas permeability.
• Protection of BF coke from the solution loss reaction in the shaft due to higher reactivity of the nut coke.

Table 3: Nut coke Quality Specification

Property 

Test Method 

Standard: TU U  19.1 -00190443 -120:2012

8 - 25 mm

10 - 25 mm

OK4

OK1 

OK2 

OK3 

 Ash content,%, max

 GOST 11022

 16,0

 11,0

 13,0

 15,0

 Mass fraction of total moisture,%, max

 DSTU ISO 579
or
GOST 27588

22,0 

 20,0

20,0

20,0

 Mass fraction of pieces of a size of, %, max

    GOST 5954.1

   

 over 25 mm

 10,0

10,0 

 10,0 

10.0 

 max 10 mm

  -

 9,0

 12,0

 15,0

 max 8 mm

 15,0

 -

 -

 - 

COKE BREEZE

Coke is a solid residue of coal carbonization at hight temperature at least of 800 - 9000C, so it no longer contains any volatile matter. Coke Breeze is customarily by-product of coke,  a fine coke separated by screening  at a mesh size of 10 mm from the larger sizes before or after crushing. 

Table 1: Quality Specifications for Coke Breeze

Property

Test Method

Standard: TUU 19.1-00190443-20:2012

Class Grade

FCM1

FCM2

FCM3

 Ash content,%, max

GOST 11022

13,0

16,0

20,0

 Mass fraction of total moisture,%, max

DSTU ISO 579 or GOST 27588

22,0

22,0

24,0

 Mass fraction of pieces of size over 10 mm, %, max

GOST 5954.1

8,0

8,0

6,0

 Fraction Class, mm

GOST 9434

0 -10

0 - 8

0 -10

0 - 8

0 -10

0 - 8