Dissertation > Industrial Technology > Mining Engineering > Beneficiation > Metallic Ore Dressing > Black Metallic Ore Dressing

Heating Phases of Pyrite and Their Magnetic Property

Author FanBoWen
Tutor WangLing
School Chengdu University of Technology
Course Mineral materials science
Keywords Pyrite Pyrrhotite Magnetite Hematite Magnetic Mineral change process
Type Master's thesis
Year 2011
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Pyrite is the most extensive in nature outputs sulfide minerals, widely used. Pyrite as a kind of rock-forming minerals, can provide a variety of important geological information; as a mineral containing gold, for gold prospecting and extraction is of great significance. To pyrite ore purification and industrial use, and provide a scientific basis for process performance, using X-ray diffraction analysis, infrared absorption spectroscopy, thermal analysis and other experimental methods to study the environment and the air at different temperatures (room temperature -1250 ℃ range, the thermostat 1h) conditions, the heating process of change pyrite mineral composition structure and variation, mineral assemblages characteristic for a more in-depth study and research on the basis of pyrite heating characteristics and mechanism of magnetic products, The main results obtained are as follows: (1) using X-ray diffraction analysis (XRD) on the air environment and different temperatures (room temperature -1250 ℃ range, the thermostat 1h) heating the product under the conditions of pyrite were systematically studied and using X'Pert HighScore software products for heating pyrite mineral phase and the diffraction peaks in-depth analysis. The results showed that the product of pyrite and the presence of heating temperature ranges are: pyrite, room temperature -700 ℃; 4H-type pyrrhotite, 500 ℃ -1200 ℃ (700 ℃ when the maximum value); magnetite, 1000 ℃ -1200 ℃ (1000 ℃ when the maximum value); hematite (final product), respectively 350 ℃ -950 ℃ (900 ℃ when maximum) and ≥ 1200 ℃. These minerals exist seven kinds of mineral assemblages: room temperature -300 ℃, pyrite; 350 ℃ -400 ℃, pyrite, hematite (trace); 500 ℃ -700 ℃, pyrite, pyrrhotite-type 4H hematite Mine (trace); 700 ℃ -950 ℃, 4H type pyrrhotite hematite; 1000 ℃ -1100 ℃, 4H type pyrrhotite magnetite; 1200 ℃, pyrrhotite, magnetite hematite (trace); ≥ 1250 ℃, hematite. And we were right pyrrhotite, magnetite and hematite may generate pathways are discussed. (2) pyrite -1250 ℃ heating from room temperature infrared absorption spectrum (400 -1 800cm -1 ), sequentially generates pyrite, pyrrhotite, magnetic hematite. Pyrite (room temperature -700 ℃), belonging to the absorption band of pyrite is 420cm -1 ; pyrrhotite (400 ℃ -1200 ℃), belonging to the absorption band of pyrrhotite is 470cm < sup> -1 , 540cm -1 ; magnetite (1000 ℃ -1200 ℃), belonging to magnetite absorption band is 565 cm -1 ; hematite (≥ 1200 ℃), belonging to hematite absorption band is 480cm -1 , 619cm -1 , 795cm ?? -1 , 1090cm -1 . (3) Air condition, pyrite from room temperature to 900 ℃ the DTA-TG-DTG curves, DTA curve appeared three endothermic valley, and accompanied significant weight loss on the TG curve response, TG curve from room temperature to 900 ℃ weight loss rate of 33.92%, due Fe 2 is oxidized to Fe 3 , there are SO 2 gas to escape, resulting in weight loss reaction . DTG curves of three peak, namely 490.0 ℃, 564.1 ℃ and 605.1 ℃, may be due to the oxidation of pyrite, hematite generated and pyrrhotite. Under argon, pyrite from room temperature to 900 ℃ the DTA-TG-DTG curves, DTA curve appeared in two endothermic valley, TG curve response with significant weight loss, TG curve from room temperature to 900 ℃ weight loss rate of 25.78%. There are two peak DTG curves, respectively, 523.3 ℃ and 673.7 ℃, probably due to the desulfurization reaction pyrite were respectively generated pyrrhotite and pyrite. (4) pyrite heated from room temperature to 1250 ℃ susceptibility change map product is asymmetrical saddle. Two peaks, the first peak at 700-800 ℃, second peak (maximum magnetic) in 1000 ℃. Specific changes in the process is as follows: 400 ℃ ago, still pyrite, magnetic virtually unchanged; 400 ℃ generated when canted antiferromagnetic hematite, magnetic susceptibility increased slightly; 550 ℃ generated when ferrimagnetic pyrrhotite ore, magnetic susceptibility increases rapidly; 700 ℃ when the most abundant pyrrhotite, susceptibility to achieve relative maximum; 1000 ℃ generated when the ferromagnetic material magnetite susceptibility maximum. Pyrite 700 ℃ under isothermal conditions, the magnetic characteristics are: 10min -1 h between the magnetic susceptibility strongest little change; 1h after decreasing susceptibility; 3h after the magnetic susceptibility is weak, stabilized. The reason is: 10min -1 h, mainly pyrrhotite and hematite content changed little; 1h after a significant reduction in pyrrhotite, hematite large increase; 3h After only one heating products hematite.

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