Изучение структурных и технологических свойств гексагональных, синтетических пирротинов

Стехиометриялы? емес пирротиндер келесі с?лба бойынша тоты?пайтын ?ыш?ылдарда ериді: ал?аш?ы еру пирротинні? ??рамыны? ?згеруімен ?атар ж?реді (к?кірт бойынша баиды). Жо?ары к?кіртті пирротин т?зілгеннен со? (Fe0,855S - Fe0,862S), еру элементті к?кіртті? б?лінуімен ж?реді.

Пирротиндерді? тоты?тырып бактериалды шаймалану процесі2 сатылы ?теді: 1-саты пирротиндер темірмен байытылады, содан со? темір сульфатыны? т?зілуімен (Fe2+) т?менгі к?кіртті сульфидтерді? еруі ж?реді.

The studying of structural and technological hexagonal, synthesize pyrrhotites properties

The aim of work is studying and establishing of structural and technological properties of nonstotichmetric, hexagonal pyrrhotites, getting from pyrite thermal decomposition in condition of limiting oxygen contention.

The analysis of literary facts show that the prediction of pyrrhotites behavior, getting from high sulfides thermal decomposition in this work was formulated at his following hydro-, pyrometallurgical treatment is possible basing on knowledge of his structural and technological features.

The products of pyrite, arsenopyrite, chalcopyrite are pyrrhotites of different compounds FeS, Fe7S8, Fe0.877S.

Kinetic researching showed that process of pyrite decomposition in vacuum describe by one-stage kinetic model - pyrite dissociation with element sulphur and pyrrhotites formatting, in air atmosphere by two-stage kinetic model А-1>В-2>С: at 556 єС is occur the formation of intermediate oxygen bearing compounds, at 650 єС with formation of pyrrhotite and elemental sulfur with following sulphur oxidizing by oxygen of gas phase. All this transformation accomplished with structural transformation from body-centered cubic arrangement to face-centered cubic lattice at 556 °С and back transition from face-centered cubic lattice to body-centered cubic arrangement at 650 °С.

The temperature of Neel in pyrrhotites decreasing with contention of sulfur; in the chalcopyrite the Neel point is appeared at 550 єС, this explaining by antiferromagnetic iron spins; the arsenopyrite magnetic phase transition from less ferromagnetic state to paramagnetic is occur at 480 °С.

Thermal decomposition of chalcopyrite accomplished with 3 stage: 1 stage - magnetic transition in Neel point at 550 єС; 2 stage - polymorphic transformation of б-chalcopyrite to в-chalcopyrite at 565єС, 3 stage - the formation of intermediate bornite, the structural transition from в- tetragonal chalcopyrite to cubic type of chalcopyrite at 590 єС. At 553 °С arsenopyrite structure is occur the transition from body-centered cubic arrangement to body-centered cubic arrangement at 800 єС and characterize by structural transition in cubic lattice in chalcopyrite by scheme face-centered cubic lattice to body-centered cubic arrangement.

Pyrite and arsenopyrite decomposition accomplish by increasing of porosity and specific surface at increasing of pyrite decomposition degree until 40-45 % at following decomposition the specific surface and porosity are decreasing - occur enlargement and confluence of minor pores this also confirm by results of microscopic analysis.

Was established the continuous (in the temperature interval from -23 before -185 єС) changing of orientation ions moments of А-lattice Fe0.88S pyrrhotite, is occur the reorientation of spins in A sub lattice, 2 others lattice are save the own parameter of hyperfine structure.

By the results of electrone-microscopic analysis established that the pyrrhotite stratiform structure formation (preferential is occur in Fe0,85S и Fe0,86S - the most sulfuric). The sulfur contention in pyrrhotite Fe0,85S stratum is achieve 53,02 at. %, in other - 40,08 at. %. Anisotrophy is content with quick inversion, which for pyrrhotites with less iron contention is occur at tempering 620 before 700 °С.

At first time was established the pyrrhotites heat capacity Fe0,855S - Fe0,888S, results showed that pyrrhotite heat capacity practically is not depending from structure and consist at єС 73,30 J/mole·єС. In Neel point the value of synthetic pyrrhotite heat capacity depending on sulfur contention (from 53,05 before 53,27) decrease from 73,42 before 73,30 J/mole·єС.

By X-ray analysis established that the crystal lattice modification of Fe0,88S, Fe0,89S and Fe0,90S pyrrhotites in the dependence from interplanar distance and pyrrhotites compounds is under the Vegard law, in crystal lattice of Fe0,85S and Fe0,86S pyrrhotites such dependence is not occur, as a reason of more sulfur quantityin such pyrrhotites.

The high-tempered x-ray established that magnetic phase transition in Neel point in pyrrhotite Fe0,85S at 320 °С degree contribute to microphase formatiom, unsoundness increasing and changing of order of cation vacansy, such structural modification are cause of by transformation of antiferromagnetic structure to paramagnetic form.

By Faraday method was established that before 240 °С in pyrrhotites Fe0,855S, Fe0,888S, Fe0,90S is occur the tempering hysteresis of magnetic properties. The reason of hysteresis is the repartition of vacancys in pyrrhotite lattice.

-potential in pyrrhotites Fe0,855S - Fe0,89S increase at pH from 5 before 13 rise. At the dependence from pyrrhotite compound, with decreasing of sulfur contention -potential decrease from 52,1 мВ Fe0,85S pyrrhotite before 40,8 мВ Fe0,89S pyrrhotite, that is mean that pyrrhotite flotability at sulfur contention at his compound decreasing.

Nonstoichmetric pyrrhotite dissolve in nonoxidizing acids by following scheme: first of all the dissolving accomplish with pyrrhotite compound modification (is occur the enrichment by sulfur). After the high sulfur contention pyrrhotites formation (Fe0,855S - Fe0,862S), dissolving go on with element sulfur isolation.

Mechanism of oxidative bacterial leaching process depends from structure of pyrrhotites. Process is consisting of two stages: 1 - pyrrhotite enrich by iron (the initial structure was Fe0,855S, after leaching - Fe0,90S), 2 - the enriching by iron pyrrhotite dissolve with appearance of iron sulfate (Fe2+).

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