Production of Formed Coke from Nigerian Coals

International Journal of Coal Geology, 2009

The demand for metallurgical coke for blast furnaces is forcing the coking industry to look for new sources of coking coals. The physical and chemical parameters of coals used in coking blends determine the quality (reactivity and strength) of the finished cokes. This study examines the technical properties of the cokes produced from various blends of three Polish coals with different coking. These coals were collected from three mines: Zofiówka, Szczygłowice, and Krupiński (Upper Silesian Coal Basin, Poland). The coal charges were coked in the laboratory scale, at temperatures of up to 1000°C, in an inert atmosphere. The coke reactivity (index CRI) and the coke strength after reaction (CSR) were measured and correlated to the properties of parent coals using statistical analysis. The result of this study shows strong relationships between the concentration of the best coking coal (Zofiówka) in the blend and the CRI and CSR of the resulting coke. The CRI and CSR parameters for cokes obtained from single coals and from their blends show the additive character. This study also confirms the linear relationship between CRI and CSR parameters of the cokes.

Petroleum & Coal, 2009

The pilot scale carbonization of the normally charged bituminous Polish Bellview coal blends was conducted in a 250kg capacity coke oven with a bulk density of 800kg/m 3 , flue temperature of 1250°C and coking time of 18 to 20 hours. The micum drum test conducted on Bellview A and B cokes gave M 10 abrasion resistance of 11.40% and 15.40% and M 40 resistance to fragmentation of 77.80% and 70.80% for Bellview coke A and B, respectively. The results of this study showed that Bellview A coal blend is of a higher bituminous grade than Bellview blend B, though its micum indices do not meet the specification of 9% (maximum) M 10 and 78% (minimum) M 40 for blast furnace ironmaking at the Nigerian Ajaokuta steel plant. It is however expected that the small deviations of +2.4% and-0.2%, in the M10 and M40 of Bellview B coke may be eliminated during industrial scale cokemaking under a higher static load and the application of coking improvement techniques such as pre-heating and stamp charging .

International Journal of Advanced Chemistry

This work illustrates the production and characterization of metallurgical coke from Duduguru coal, Obi local Government Area of Nasarawa State, Nigeria. The analytical assessment of properties such as proximate analysis, elemental composition, and calorific value are very important to know the coking qualities of the coal. The proximate analysis showed that the moisture content, ash content, volatile matter, fixed carbon and calorific values of the coal are; 1.86%, 18.82%, 43.74%, 53.58% and 5405.15 Cal/g respectively. Based on the result of the proximate analysis, the coal is of good metallurgical coke quality from an industrial prospective and heat generation is to be considered. Elemental analysis shows that due to the low heavy metals, low sulfur content and ash content of the coal, utilization of the coal within a safe environment is feasible with just a little environment impact and make it suitable for blending with strong coking or caking properties.

ISIJ International

Sequential coal briquetting and carbonization was applied to preparation of cokes from 9 non-or slightly caking coals with carbon contents (f C) of 67-85 wt%-daf. Coal pulverization to sizes of < 106 μm and briquetting at 40°C enabled to prepare cokes with tensile strength (σ) over 10 MPa from 4 coals with f C of 82-85 or 67 wt%-daf. Then, by introducing fine pulverization to sizes of < 10 μm before the briquetting, 7 coals were converted successfully into cokes with σ = 11-25 MPa. Increasing the briquetting temperature to 240°C further increased σ to 19-35 MPa for all the 9 coals. It was thus demonstrated that the hot briquetting of finely pulverized coal was a method to prepare high strength coke regardless of the rank of parent coal. Cokes were also prepared from 14 binary coal blends. All the cokes prepared by applying the fine pulverization and hot briquetting had σ of 20-35 MPa, which agreed well with that calculated by weighted average of those from the component coals. On the other hand, positive and also negative synergistic effects of blending occurred when blends were briquetted at 40°C. Characteristics of bonding/ coalescence among particles of different types of coals were responsible for such synergies.

ISIJ International, 2019

In the present study, we prepare several types of specimens from non-caking coal-including specimens in which noncovalent bonds between O-functional groups in coal are cleaved by pyridine and HPC-derived thermoplastic components are introduced into the pores produced by swelling, as well as specimens consisting of physical blends with HPC-and examine the influence of heating conditions and types of caking agents on the production of high-strength coke using a SUS tube. We also investigate the influence of heating conditions and types of caking agents on the strength of coke from pelleted specimens and determine the optimal conditions for producing high-strength coke from non-caking coal. HPC with a wide range of thermoplastic properties is more effective as caking agents than additives containing only low-molecular-weight or high-molecular-weight components. In addition, the strength of the produced coke depends on the amount of the additive, and optimal values of the additive amount are present. It was found that the following heating schedule is effective for producing high-strength coke from noncaking coal with added caking agents: First, high-speed heating (20°C/min) to an intermediate temperature in the range 400-600°C, recognized as the thermoplastic temperature range for typical caking coal; then, low-speed heating (3°C/min) to the temperature range of 900-1 000°C. Moreover, we demonstrate that, by increasing the rate of heating in the thermoplastic temperature range, it is possible to reduce the amount of caking agent added.

Journal of Minerals and Materials Characterization and Engineering, 2007

A mathematical model and its associated numerical search algorithm has been developed for routine coal blending to include local coals for cokemaking at the Nigerian blast furnace-based Ajaokuta Steel Plant. A typical binary blend proposed using the model includes 28.38% and 29.00% of the ash-laden Lafia and non-caking Okaba coals, respectively. The proposed blends satisfy basic chemical and mechanical strength requirements at the lowest cost per ton of coal. The blending calculations showed that only low ash, low sulphur, medium volatile and high vitrinite reflectance prime grade coals such as the UK Ogmore should be imported for blending with the ash-laden medium coking Lafia coal. When the proposed blends are successfully confirmed with bench and pilot scale carbonization tests, cokemaking at Ajaokuta will be conducted with substantial savings in foreign exchange.

International Journal of Chemistry and Materials Research, 2015

Thermochemical decomposition of Ondo tar-sand was carried out at a temperature of between 190-250°C in a constructed metal retort, and a yield of 66.66 % bitumen was obtained. Some important parameters of coal for blend simulation, such as the rheological and agglomerating properties of coal samples from-Garin Maiganga (GMG), Chikila (CHK), Lamza (LMZ), Shankodi-Jangwa (SKJ), Afuzie (AFZ) were determined by Gray-King assay test to assess their suitability for blending in coke making. The results showed that all the coals had poor thermoplastic properties that cannot agglomerate on heating because of their low level of fluidity, even though SKJ had an appreciable coke yield of 82.60 % with coke type C indicating that it was weakly coking. Thereafter, formulation of binary blend of coal-bitumen by weight (10 % bitumen and 90 % pre-heated coal samples at about 150 o C) was carried out. And the feasibility of the blend for industrial coke production was investigated by physico-chemical analysis, which revealed that the coking properties of the blend had been improved: Gieseler fluidity/plastic property in dial division per minute (DDPM) for LMZ = 76; CHK = 15; AFZ = 37; GMG = 18 and SKJ = 390, which might produce metallurgical coke with good chemical and mechanical properties.

ISIJ International, 2011

Coke and Chemistry, 2009

The influence of various technological factors on the high-temperature properties of coke is investigated. It is found that factors facilitating an orderly organic structure of the coke (fine grinding and compaction of the batch, increased conditioning of the coke, dry slaking, the introduction of lubricant additives in the batch) reduce the reactivity of the coke; by contrast, introducing coke fines, intermediate product, and red mud in the batch increases the reactivity.

2007

A series of coking coals covering a wide range of coalification, thermoplastic properties and geographical origin were carbonized at two different scales. All the coals used are available in the international market and they are used by the cokemaking industry in blend preparation. The cokes were produced in two movable wall ovens of 15 and 300 kg capacity available at INCAR-CSIC facilities. The quality of the cokes was assessed by means of reactivity towards carbon dioxide and mechanical strength before and after the reaction with CO2. The results obtained are very promising and a good correlation between the quality parameters of the cokes produced in the two ovens was found. The use of a semi-pilot oven against big-capacity ovens in the optimization of complex coking blends allows to obtain valuable results by using small amount of coal (15 kg vs. 300-400 kg) with the advantages that it is quicker, more flexible and of lower cost.