A novel process for the preparation of an ultra-clean superfine coal–oil slurry is presented. The process uses a high-pressure water-jet mill and a pumping slurry jet mill for coal superfine comminution. The mean diameter of coal particles in the slurry is 2.71 μm, and the ash content is 1.05%. The stability, rheological behavior, and heat value of the slurry are investigated. The results show that the ultra-clean superfine coal–oil slurry has a high heat value, a high level of stability, and low viscosity. The slurry can be used as fuel in a high-speed diesel engine. The total energy consumption of comminution of the coal particles to reduce the mean diameter from 3 mm to about 2.71 μm is 124 kW h per ton, which is lower than the total energy consumption by traditional ball mills by about 50–70%.

A novel process for the preparation of ultra-clean micronized coal is presented in this paper. High pressure water jet mill replacing the ball mill is employed for coal comminution in the new preparation process, which is the essential difference from the traditional one. To compare the new preparation process with the traditional one, the comparison experiments were performed, with froth flotation tests of the fine particles ground by both mills using 0# diesel oil and n-dodecane as collector, 2-octanol as frother, and sink–float separation tests using mixtures of carbon tetrachloride–benzene and carbon tetrachloride–bromoform as dense liquid. Different parameters including combustible recovery, ash content of the clean coal, separation efficiency, and energy consumption were investigated based on the two different preparation processes. The results show that the new preparation process has high combustible recovery, low ash content of the product, high separation efficiency, and low energy consumption compared with the traditional one.The comminution mechanism of high pressure water jet mill is introduced in this paper. The high pressure water jet comminution technique has great potential in coal pulverization, having the advantages of low energy consumption, low iron content, and low equipment wear.

A novel process for the preparation of ultra-clean micronized coal is presented in this paper. High pressure water jet mill replacing the ball mill is employed for coal comminution in the new preparation process, which is the essential difference from the traditional one. To compare the new preparation process with the traditional one, the comparison experiments were performed, with froth flotation tests of the fine particles ground by both mills using 0# diesel oil and n-dodecane as collector, 2-octanol as frother, and sink–float separation tests using mixtures of carbon tetrachloride–benzene and carbon tetrachloride–bromoform as dense liquid. Different parameters including combustible recovery, ash content of the clean coal, separation efficiency, and energy consumption were investigated based on the two different preparation processes. The results show that the new preparation process has high combustible recovery, low ash content of the product, high separation efficiency, and low energy consumption compared with the traditional one.The comminution mechanism of high pressure water jet mill is introduced in this paper. The high pressure water jet comminution technique has great potential in coal pulverization, having the advantages of low energy consumption, low iron content, and low equipment wear.

In this paper, infrared thermal testing and mathematical models for studying the temperature distributions of the high-speed waterjet in air are presented. The waterjet temperature distributions are investigated under different pressures. We describe the experiments in which we apply the infrared thermal imager to obtain the infrared thermal images of the high-speed waterjet. By denoising these infrared thermal images and fitting data, we obtain the isotherms and the temperature variation curves as a function of the distances form the nozzle outlet. In order to calculate the shear stress within the water air boundary layers, multi-phase models are developed. Due to the sophisticated patterns of the multi-component model, the numerical computation is used to obtain the velocity and temperature distribution of the waterjet. The results indicate that the temperature distributions were similar when the pressure is greater than the threshold pressure. This fact is proved by further theoretical computation and experiments data. The paper revealed that the velocity profiles were similar to the temperature profiles in the radial direction at the same cross-sections.

In this paper, infrared thermal testing and mathematical models for studying the temperature distributions of the high-speed waterjet in air are presented. The waterjet temperature distributions are investigated under different pressures. We describe the experiments in which we apply the infrared thermal imager to obtain the infrared thermal images of the high-speed waterjet. By denoising these infrared thermal images and fitting data, we obtain the isotherms and the temperature variation curves as a function of the distances form the nozzle outlet. In order to calculate the shear stress within the water air boundary layers, multi-phase models are developed. Due to the sophisticated patterns of the multi-component model, the numerical computation is used to obtain the velocity and temperature distribution of the waterjet. The results indicate that the temperature distributions were similar when the pressure is greater than the threshold pressure. This fact is proved by further theoretical computation and experiments data. The paper revealed that the velocity profiles were similar to the temperature profiles in the radial direction at the same cross-sections.