| In recent years, coke has been increasingly demanded and its price has been rising around the world. However, a large quantity of coke breeze is treated cheaply or even abandoned, which is generated from the process of production, crushing, transportation and application of coke. Therefore, if coke breeze can be recycled to prepare formed coke, which recovers its function as lump coke, it would be of great significance on value promotion of coke breeze, environmental protection and saving fine coal resource such as coking coal, fat coal, and etc.In this paper, study was conducted on the preparation of high strength formed coke with coke breeze as raw material, coal tar pitch as binder activated by an assistant reagent BJ. A technological flow including compressing, volatilizing and carbonizing as main procedures was developed. The consolidation mechanism of formed coke was also studied.The study showed that, the reagent BJ has activating effect on coal tar pitch, which enables the pitch to show good bonding action at ambient temperature. By adding reagent BJ, it realized that coke breeze be compressed at ambient temperature with coal tar pitch as binder, and briquette be produced with high mechanical strength both in wet or dried state. Under the condition of coke breeze compressing with pitch addition of 12 wt%, compressing pressure of 35MPa, moisture of 13wt%, and the particle size distribution of 32.5% of -0.45mm,16.75% of 1～0.45mm, 48.2% of 3～1mm,2.55% of 5～3mm, without adding BJ, the drop resistance of wet briquette was 0, drop resistance and compressive resistance of dried briquette were 10.6/(2m) and 5.54MPa respectively. While reagent BJ was added by 2.4ml/(100g coke breeze), the drop resistance of wet briquette reached more than 50/m, and the drop resistance and compressive resistance of dried briquette reached 44.7/(2m) and 11.38Mpa respectively.Based on thermal behavior of binders, heat treatment technology of volatilization followed by carbonization was developed for formed coke from coke breeze with BJ activated coal tar pitch as binder. The reslults showed that, when comparing with typical technologies whose briquettes are carbonized directly at high temperature, the new process lowered the carbonization temperature and shortened carbonization time and produced well bonded formed coke by volatilizing at air atmosphere prior to carbonizing at N2 atmosphere. The strength reached 14.07Mpa as wet biquette was volatilized at 370℃for 20min, and then reached 21.30Mpa after carbonzed at 550℃for 30min, while it was only 12.64 Mpa when the wet briquette was directly carbonized at 550℃for 30min. Thus, volatization was a key procedure to make formed coke consolidate completely.The high strength formed coke prepared in this study exhibited favorable quality as the compression strength was above 21Mpa, coke reactivity index was 30.31% and coke strength after reaction was 30.88%, which was equivalent with common coke and DKS formed coke.There are many advantages of this formed coke process, such as good product quality, compressing at ambient temperature, low temperature heating, short time heating, simple process flow, raw material preheating free, drying procedure negligible, low energy, and low cost. Therefore, it has a broad application prospect.Study on consolidation mechanism of formed coke showed that, in the process of volatilization and carbonization, reagent BJ promoted the decoposition, polymerization and condensation of pitch, which resulted in the formation of sclerotic films on the surface of coke breeze particles and carbon chain bridges among the particles. Thus the particles were bonded firmly, and formed coke with suitable strength and macroscopic homogenous quality was obtained. The consolidation mechanism can be presented by the formula C+CxA+C→C-Cn-C+CmA.
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