Heating Phases of Pyrite and Their Magnetic Property
|School||Chengdu University of Technology|
|Course||Mineral materials science|
|Keywords||Pyrite Pyrrhotite Magnetite Hematite Magnetic Mineral change process|
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 sup> 800cm -1 sup>), sequentially generates pyrite, pyrrhotite, magnetic hematite. Pyrite (room temperature -700 ℃), belonging to the absorption band of pyrite is 420cm -1 sup>; pyrrhotite (400 ℃ -1200 ℃), belonging to the absorption band of pyrrhotite is 470cm < sup> -1 sup>, 540cm -1 sup>; magnetite (1000 ℃ -1200 ℃), belonging to magnetite absorption band is 565 cm -1 sup>; hematite (≥ 1200 ℃), belonging to hematite absorption band is 480cm -1 sup>, 619cm -1 sup>, 795cm ?? -1 sup>, 1090cm -1 sup>. (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 sup> is oxidized to Fe 3 sup>, 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 sup> 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 sup> 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.