Gold Extraction Technology Of The Preparation Of Activated Carbon Pore Structure Analysis

This paper proposes a new technique of preparation for activated carbon (AC) used for extracting gold by microwave irradiation, which realizes that quality of the product is characterized by stability, high efficiency, energy-saving and pollution-safe, paves a new way of manufacturing AC used for extracting gold and has the practical importance.This paper discusses manufacturing AC used for extracting gold by the way of conventional heating and microwave irradiation in the laboratory scale and makes comparison of the results. At the same time, kinetics of water vapor activation by the way of conventional heating is studied and its reaction mechanism is discussed primarily. A device of microwave irradiation is developed based on the laboratory scale and the pilot experiment is made as well.Through the conditional experiment, the optimum technical conditions, preparing the activated carbon from the coconut shell char with water vapor activation by the way of conventional heating, are determined as follows: activation temperature 900 ℃ , activation time 60min, flux of water vapor 2.83g/min, iodine adsorption of the activated carbon to be made 1019.85mg/g, methylene blue adsorption value 12ml/0.1g and yield 43.81%.;Through the orthogonality experiment, the optimum technical conditions, preparing the activated carbon from the coconut shell char with water vapor activation by the way of microwave irradiation are determined as follows: microwave power 700W, activation time 20min, flux of water vapor 3.25g/min, iodine adsorption of theactivated carbon to be made 1023.23mg/g, methylene blue adsorption value 14ml/0.1g and yield 42.27%. Compared with the conventional process, microwave radiation process has advantages of shorter flow, higher efficiency, less pollution and better economic benefit.Through nitrogen adsorption measurement at low temperature, adsorption isotherm of AC on the condition of the optimum technology is measured, resulting in general pore volume obtainable. Surface area of AC is calculated by BET method, AC micropores distribution is analyzed by H-K method, surface area of AC and pore volume of micropores are counted by D-A method, mespores distribution is analyzed by BJH method, pore size distribution is obtained by DFT theory, and its microstructure is analyzed by scanning electron microscopy. These results demonstrate that AC used for extracting gold by microwave irradiation is better than that by conventional heating in the fields of surface area, pore volume and content of micropores and has richer porous structure.Furthermore, kinetics of the coconut shell char preparation by conventional heating is studied, apparent energy (Ea) is calculated to be 74.47KJ/mol and reaction mechanism of AC preparation is discussed briefly.Through self-developing microwave device, research of producing the activated carbon used for gold-extracting has been made. Applying the conditional experiment, the optimum technical conditions are defined: microwave power 60KW, speed of rotation lOOrad/min and pressure of water vapor O.OlOMPa. The value of iodine adsorption keeps 1072 mg/g -1085 mg/g, that is to say, product'squality is stable, and exceeds national level A of AC used for extracting gold in the status of continuous production. The device possesses characteristics of continuous adjustment to microwave power and high automation. Manufacturing AC used for extracting gold in a stable and continuous way comes into reality.