A Microscopic Numerical Simulation of Carbon Dissolution in Different Coke Shapes in the Dripping Zone of Blast Furnace

The carbon dissolution of coke pieces in hot metal mainly influences the carbon content and carbon saturation temperature in the ironmaking process. The liquid metal and slag start to drop down in the dripping zone (DZ) which is located the lower part of blast furnaces. The dissolution of carbon in liquid metal and slag droplets passing the stagnant hot gas flow in the fixed coke bed of the dripping zone were observed by a multi-droplet model based on the Computational Fluid Dynamics (CFD) method. The uniform-coke pattern was set in the model following the preferred distribution of a one-layer packed bed from a water droplet experiment. The different coke shapes relating to the shape factor from 0.75-1.0 were observed in a 40mm-coke bed. For one-time drainage, the carbon dissolution slightly increased after flow in the coke bed zone and showed a high percentage on the coke surface. The concavity and convexity of coke pieces have more effect on the interaction between liquid and coke surface. Besides, the carbon dissolution can be investigated to approach the coke consumption in one coke channel and estimate the carbon content and carbon saturation temperature of liquid metal after draining.

Diamond growth from organic compounds in hydrous fluids deep within the Earth

At subduction zones, most diamonds form by carbon saturation in hydrous fluids released from lithospheric plates on equilibration with mantle rocks. Although organic molecules are predicted among dissolved species which are the source for carbon in diamonds, their occurrence is not demonstrated in nature, and the physical model for crustal diamond formation is debated. Here, using Raman microspectroscopy, I determine the structure of carbon-based phases inside fluid inclusions in diamond-bearing rocks from the Alps. The results provide direct evidence that diamond surfaces are coated by sp2-, and sp3-bonded amorphous carbon and functional groups of carboxylic acids (e.g., carboxyl, carboxylate, methyl, and methylene), indicating the geosynthesis of organic compounds in deep hydrous fluids. Moreover, this study suggests diamond nucleation via metastable molecular precursors. As a possible scenario, with carbon saturation by reduction of carboxylate groups, I consider tetrahedral H-terminated C groups as templates for the growth of sp3-structured carbon.