Impact of transportation on foundry coke quality

The quality metrics of foundry coke are determined by testing at coke plants. Foundry coke consumers are foundry enterprises which are usually located far from the coke plants. Foundry coke is transported in bulk in open railway wagons. Therefore, this paper is aimed to determine the impact of transportation on the quality of foundry coke. The test conditions were as close as possible to real life conditions of foundry coke transportation. To estimate the impact of transportation distance we introduced the destruction index Pт (%). The results of experimental studies have shown that the destruction of foundry coke is not the same at different intervals of transportation. When transporting up to 300 km, the coke with the minimum durability index M40 is destroyed. When the distance is increased from 900 km up to 2500 km, the foundry coke destruction index (Pт , %) increases by 2.08 – 3.02 % depending on the batch. For all batches, a size fraction of less than 40 mm was noted depending on the durability index M40 from 0.25 to 1.41 %. The size fraction of more than 80 mm stays the same for foundry coke with higher durability indices. When the air humidity rises by 40 % during transportation, the amount of moisture in the coke samples of a 40 – 60 mm size fraction is more than 24 times higher than usual, a 60 – 80 mm size fraction – more than 17 times, an 80 mm and larger – more than 10 times. When the air humidity decreases by 34 %, the amount of moisture in a gram of coke of a 40 – 60 mm size fraction becomes 2 times lower than usual, a 60 – 80 mm size fraction – 1.26 times, an 80 mm and larger – 1.45 times. Compared to coke of size fractions 60 – 80 mm and 80 mm and larger, the moisture of the 40 – 60 mm size fraction coke grows faster when the air humidity increases as well.

Evaluation and validation of technical procedure for foundry coke mechanical strength testing

Foundry coke is a special type of coke with lumps size usually bigger than 100 mm. Therefore it is difficult to asses its physical properties representatively for whole lot. There exist international standards for coke sampling and testing strength index (usually Micum test). Nevertheless companies dealing with foundry coke notified problems with methodology of sampling and sample preparation for the test. Manual sampling according to ISO 18283 is very labour extensive and with connection with literally proceeding with ISO 566 gives non-representative results for foundry coke +100 mm. For this reason on the basis of these standards there was evaluated procedure for coke sampling and testing strength indexes which is more practical for plant routine use and gives more reliable results in comparison to international standard. This article presents results of work aimed at checking usability of ISO standards provisions for foundry coke testing and evaluation and validation of simplified procedure.

An efficient method of foundry and metallurgical coke quality improvement

At foundry coke production, introduction into a coal burden comparatively small amount of non-sintering carbonaceous additives is one of effective methods of the coke mechanical, physical and chemical properties intended control. A review of industrial tests on coal burdens coking with different thinning additives, carried out at coking plants of Western Siberia and the Urals, presented. Coke dust of coke dry quenching facility was used as additives, as well as oil-coke and semi-coke fines, and rubber crumb. Under industrial conditions of JSC “Altaj-koks” and JSC “Koks” coke dust of coke dry quenching facility was tested as a thinning additive. After introduction into the burden of 1.6–3.0% of coke dry quenching facility dust, the coarseness and mechanical strength of foundry coke increased. The industrial burden coking with oil-coke fines was accomplished at JSC “Altajkoks” Nos 1 and 2 coke-oven batteries. Oil-coke fines in the amount of 5% was added to a burden (у = 15–16 mm) without change of coking regime (the period of coking is 15–16 h). Strength of foundry coke (М40) increased by average 0.5%, of BF coke – by 1.2%, ash content decreased by 0.3%, sulfur content increased by 0.03–0.06%, reaction ability decreased by 19% (rel.). At the OJSC “Gubakhinsky koks” it was determined by industrial tests, that it is possible to produce a metallurgical coke, meeting requirements of non-ferrous metallurgy, providing up to 5% of oil-coke fines are added instead of the same amount of low-sintering coals. VUKHIN’ studies showed, that still higher effect in improving foundry and BF coke quality can be reached by introducing into the coal burdens “modified” oil coke up to 50% as a coking additive. During industrial tests at JSC “Altaj-koks” semi-coke fines were introduced into production burden instead of KCH coal in the amount of 3–7%. At its utilization a burden crushing degree decreased down to 76.5%, dust content (class 0.5–0 mm) decreased down to 39.1%, its bulk density increased up to 780 kg/m3 . At that the coke mechanical strength corresponds to that for coke made of industrial burden, and its coarseness increased. Results of successful industrial tests of foundry coke made of burdens with coke dry quenching facility dust and oil coke fines at smelting in cupola gray cast iron and malleable cast iron.