What causes coke to turn black with a granular and rough surface?

From my experience, a higher proportion of lean coal in the coal blend leads to the presence of granular coal lumps. A larger crushing particle size of lean coal also leads to the same issue. The washing water contains too many impurities, causing the surface of the coke to turn black.

The amount of colloids seems low, as well as the degree of adhesion; it is estimated that the volatile content in your coke is high while the M10 value is low. Check the furnace temperature as well as the G and Y values of the coal fed into the furnace

I. Analysis from the coal blending formula: 1. It is possible to determine whether the coal blending is reasonable by analyzing the coal lithology, as well as whether the vitrinite reflectance falls within an optimal range. 2. If coal rock analysis is not available, it is also possible to determine whether the conditions are reasonable by using indicators such as the vitrinite thickness Y in conjunction with the coal caking index G. II. Analysis from process parameters 1. Whether the fineness of the coal fed into the furnace is appropriate, and whether there is any segregation in the storage area. 2. Whether the heating regime is appropriate, and whether horizontal and vertical heating are suitable; this phenomenon often occurs when the coke is over-processed. III. Identifying the cause through comprehensive coke analysis – Analyze values such as M25, M10, CSR, CRI, and Vdaf of the coke.

Reply to 4# rxscb: How to detect whether there is segregation when material is put into storage.

Check for coal material segregation: 1. In the case of ramming, the uniformity of the feed granularity can be assessed by using the ramming rocker arm of the side-loading coal car. 2. In the case of top loading, it can be determined by analyzing the uniformity of coal fineness in the hopper of the coal loading vehicle.

I’m not sure what the strength of the coke produced by your plant is. If the coke strength is low, it might be due to insufficient bonding of the coal fed into the furnace; such a situation can occur when the temperature at the furnace tip is too low

I agree with the view from the second floor; it mainly depends on the type and composition of the coal used for blending

The fineness of the lean coal is insufficient, the cohesion of the blended coal is inadequate, and the heating temperature is not appropriate.

The coal blending fineness is insufficient, the coking maturity is poor; also, is the moisture content during coke quenching too high?

This situation has also occurred in our factory; the surface particles are earthy yellow. Could it be that coal contains gangue?