Control coke sulfur content

The sulfur content in coke is brought in by the sulfur content of the coking coal; to control the sulfur content in coke, the following measures must be taken: 1. Strictly control the sulfur content specifications for coking coal； 2. Based on the grade of the coke to be produced, coal should be blended appropriately to keep the sulfur content of the blended coal within the required limits.

The conversion rates of sulfur of different origins in coal – such as organic sulfur, pyrite sulfur, or inorganic sulfur (sulfates, etc.) – during the coking process (i.e., the amount that remains in the coke and the amount that ends up in the gas) vary, and this affects the sulfur content of the final coke. Therefore, a detailed analysis of the sulfur content in the incoming coal and the coal blends is necessary in order to accurately predict the sulfur content in the coke. In practice, paying extra attention to coals with particularly high sulfur content within a single coal type and ensuring precision in their blending is also a measure to avoid unexpected fluctuations in sulfur content in coke.

In general coal blending, it is necessary to control the total sulfur content of the blended coal; by doing so, it is possible to predict and control the sulfur content in the coke. This method is advantageous for small-scale coking plants. In coal blending at large coking plants, in order to improve economic efficiency and ensure strict control, organic and inorganic sulfur, as well as pyrite sulfur, are generally measured, as mentioned above. However, the conversion rates of the three types of sulfur vary during the coking process: 65% of the organic sulfur can be converted into gas and volatilized, while inorganic sulfur remains mostly in the coke. Some of the sulfur from pyrite is converted, but the majority still remains in the coke. If the coal supply is stable, the coking ratio and sulfur conversion rate can be basically determined through tests using small coke ovens. It is advisable to use bitcoals with a high content of organic sulfur. Please point out any mistakes in what I’ve said, so that we can learn together and improve.

It is likely that most of the thiophene sulfur in sulfate sulfur and organic sulfur remains in the coke. Thiols, thioethers, and other compounds containing organic sulfur, as well as sulfur from pyrite, can all be decomposed. However, in coke ovens, especially after the formation of semi-coke, the reduction in hydrogen supply causes some of the sulfur present in the gas to be converted back into coke, either in the form of sulfates or as thiophene sulfur. Just a humble opinion; I hope for your guidance!