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Carbon monoxide reduction decomposition of phosphogypsum

Author: DuYaLei
Tutor: MaLiPing
School: Kunming University of Science and Technology
Course: Environmental Engineering
Keywords: Phosphogypsum Carbon monoxide Reductive decomposition Thermodynamics Dynamics
CLC: TQ177.3
Type: Master's thesis
Year: 2010
Downloads: 90
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Abstract

Phosphogypsum is a byproduct of the production of phosphoric acid phosphoric acid process, The phosphogypsum generation and emissions cause potential harm to the environment, while wasting a huge human, material and financial resources. Faced with the pressure of the economic losses and environmental protection policies, the phosphogypsum massive resource has become the key to achieving sustainable development of phosphorus chemical industry. Phosphogypsum decomposition of the sulfuric acid is the the phosphogypsum most potential means of resource, but phosphogypsum decomposition temperature of the high energy consumption, this article focused on the issue of carbon monoxide reductive decomposition of phosphogypsum resource for phosphogypsum The technology provides the basic data and theoretical reference. HSC Chemistry, Chemical Engineering Thermodynamics software to investigate the thermodynamic behavior of carbon monoxide reductive decomposition of phosphogypsum. Reaction Equation module calculates the carbon monoxide reduction of 20 chemical reactions that may be involved in the process of decomposition of phosphogypsum molar Gibbs free energy change (△ rGm in) molar enthalpy change (△ rHm), molar entropy change (△ rSm) results indicate that these The chemical reaction most of the endothermic reaction, which is also the phosphogypsum to restore the main reason for decomposition of high energy consumption. Equilibrium Composition module simulates the thermodynamic equilibrium composition, carbon monoxide reduction decomposition of phosphogypsum that most of the reaction occurs in the course of the reaction is the coupling of two or more reactions, rather than independently of each other individually occur, wherein CaS04 (s) 4CO (g) = CaS (s) 4C02 (g) and CaS04 (s) 1/3CaS (s) = 4/3CaO (s) 4/3S02 (g) and CaS04 (s) 1/3CaS (s) = 4 / 3CaO (s) and the CAS (s) 3C02 (g) = CaO (s), S02 (g) 3CO (g) coupling occurs is the main line of the entire reaction process. By scanning electron microscopy (SEM) observation of the morphology of the phosphogypsum, the results show that phosphogypsum irregular tabular grains, strong agglomeration between particles, agglomerated particles have a large number of voids. By X-ray spectroscopy (EDS) analysis of phosphogypsum elements, the results show that the major element composition of the phosphogypsum is oxygen, sulfur, silicon and calcium species, but different micro ingredient may also vary. Phosphogypsum material phase composition was characterized by X-ray powder diffraction (XRD) results show that the major phase of phosphogypsum as CaS04 · 2H20, in addition to a small amount of SiO2. By laser particle size analyzer the phosphogypsum particle size, the results show that the particle size of the phosphogypsum approximated by a normal distribution. Influencing factors of carbon monoxide decomposition of phosphogypsum using thermal analysis techniques, the results show that the reducing atmosphere is conducive to the decomposition of phosphogypsum; carbon monoxide atmosphere, the decomposition of phosphogypsum consists of two phases, the first stage of dehydration of phosphogypsum stage the reductive decomposition stage, the second stage of phosphogypsum, 5 wt.? Cl2 admixtures favor the phosphogypsum reductive decomposition of carbon monoxide. Carbon monoxide atmosphere the phosphogypsum restore the dynamic behavior of the decomposition stage, that the whole process is controlled by chemical reaction, the kinetic equation for kinetic compensation effect lnA of = 0.1115E 0.0211, activation energy with phosphogypsum conversion percentage increase decreases.

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