Wyniki wyszukiwania - Biblioteka Nauki

1

A review of investigations into the management of gangue in the flotation of platinum group minerals

100%

O’Connor C. , Wiese J. , Corin K. , McFadzean B.

Physicochemical Problems of Mineral Processing

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2018

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tom Vol. 54, iss. 4

1107--1115

EN

The Bushveld Complex of South Africa contains almost 90% of the world’s reserves of platinum group minerals (PGMs). In the flotation of PGMs, there are significant challenges arising from the need to treat ever-decreasing grades of the relevant ore deposits. The major challenge in the flotation of these ore bodies is the control and management of the gangue minerals, particularly silicates such as orthopyroxene, plagioclase feldspar, and pyroxene which are often rimmed with talc which makes them naturally floatable. It has been shown that various polysaccharide depressants such as CMC and guar have different properties in terms of depressing the gangue minerals. Since the PGMs are often associated with sulphides, copper sulphate is widely used as an activator in PGM flotation but can inadvertently activate the gangue minerals as well as reduce the recovery of PtTe2 which accounts for up to 40% of the Pt in the Platreef ore body. Depressants also reduce the mass of solids reporting to the froth and can thus destabilize the froth. This effect on the froth can be mitigated by using higher frother dosages or water of higher ionic strength. In summary due care needs to be taken to carry out site test work to develop an optimum ratio of collector, frother, activator and depressant to ensure that the highest grades and recoveries of the PGEs are obtained while reducing depressant dosage as much as possible. Chromite recoveries can be reduced through the application of gravity separation or reducing entrainment through reduced water recovery.

2

Reductive roasting of chromite present in chromite ore uder the co gas atmosphere

100%

Potulska A.

Prace Naukowe Instytutu Górnictwa Politechniki Wrocławskiej. Konferencje

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2004

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tom Vol. 107, nr 39

263-270

EN

The reduction of chromium (IV) in industrial pellets and ore lumps was investigated by the thermogravimetric analysis (TGA). The main goal of the study was to examine in different temperature zones the behaviour of a sample consisting of industrial pellets mixed with lumpy ore and coke. The experiments were done under the carbon monoxide atmosphere in an electrical arc furnace. The sample composition (ratio between industrial pellets coke and ore lumps) was kept similar to the material used by industry to check the validity of the laboratory (one-element sample) experiments. The experimental work was performed in an electrical vertical arc furnace at the research laboratory in Delft University of Technology. During the research the kinetics of the chromite reduction in the temperature range of 1420-1520 °C were discussed. Samples were also studied using visual observations. The chromite ore tested during the experiments came from the mine in Finland.

3

Application of multiple linear regression (MLR) analysis for concentration of chromite tailings by the flotation

88%

Deniz V.

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tom Vol. 56, iss. 4

579--589

EN

In this study, the concentration of chromite minerals by amine flotation of a chromite tailing (slime) with content 23.84% Cr2O3 from Yeşilova-Burdur (Turkey) was investigated. In experimental studies, firstly, some operating parameters of the rougher flotation observed for a low-grade chromite tailing were investigated. Secondly, multiple linear regression (MLR) analyses were performed to determine the effects of some operating parameters on the performance of the rougher amine flotation. From the experimental results, multiple linear regression equations were developed to predict the recovery and grade of the chromite concentrate, and the regression coefficients between experimental and predicted values were found to be quite good (R2 values of 0.772 and 0.917, respectively). Additionally, it was found that the conditioning time and low pH value using H2SO4 showed an important effect on the recovery and the grade of the chromite concentrate.

4

Effect of particle shape properties on selective separation of chromite from serpentine by flotation

88%

Guven O. , Serdengecti M. T. , Tunc B. , Ozdemir O. , Karaagaclioglu I. E. , Çelik M. S.

Physicochemical Problems of Mineral Processing

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2020

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tom Vol. 56, iss. 5

818--828

EN

Although many studies have been conducted on the morphological variations and its effects on flotation recoveries of a single mineral system, a systematic study for the flotation behavior of mixtures of minerals has not dwelled much. In this study, th flotation behavior of chromite and serpentine minerals was investigated to distinguish and isolate the contribution of morphology in single and binary systems. For this purpose, the shape analyses for the minerals ground as single and mixture were performed, and their flotation behaviors determined with the micro-flotation experiments. Additionally, the zeta potential measurements were carried out in the presence of sodium oleate as a collector. The shape analysis of the ground samples showed that while the roundness values of chromite and serpentine (gangue) minerals as single were quite different, the particle shape of chromite favored serpentine in the mixture system which in turn suggested that the mineral with the high hardness value dominates the shape characteristics in binary grinding conditions. Accordingly, while the flotation characteristics of chromite in the mixture followed the same trend with the flotation of a single chromite system as a function of particle shape, almost a reverse trend was obtained for the shape and flotation of serpentine in the mixture compared to a single serpentine system. Thus, at roundness values of chromite particles from 0.797 to 0.732, the flotation recoveries of chromite in the mixture increased from 51.0% to 75.4%. On the other hand, likewise chromite, the flotation recoveries of serpentine increased from 20.0% to 37.3% proportional to the roundness range of 0.757 and 0.709. These findings in turn showed that the grinding conditions dictate the soft component to be monitored by the harder and denser component which dominates the angularity and floatability of the mixture.

5

Concentration of chromite by means of magnetic carrier using sodium oleate and other reagents

75%

Ucbas Y. , Bozkurt V. , Bilir K. , Ipek H.

Physicochemical Problems of Mineral Processing

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2014

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tom Vol. 50, iss. 2

767--782

EN

Chromite recovery was studied using a magnetic carrier technology. Heavy media grade magnetite was used as the magnetic carrier. The effect of various reagents such as sodium oleate (NaOl) as a collector and carboxymethyl cellulose (CMC) as well as quebracho tannin as depressants on chromite removal was investigated. The effects of pH and reagent dosages were also determined. First, the zeta potential measurements were performed for different minerals in the absence and presence of NaOl, and then magnetic carrier tests were carried out under conditions based on zeta potential measurements. The magnetic carrier tests performed in the case of individual minerals (i.e. single minerals) showed that chromite (recovery of 95.1%) could be separated from serpentine (recovery of 3.2%) whereas it could not be separated from olivine. The best chromite concentrates containing 42.1% Cr2O3 were obtained with a 76% recovery from a synthetic mixtures of chromite and serpentine under optimum test conditions, that is at pH 10.5, 5.10–5 M NaOl, 20 g/Mg CMC, 0.5 g magnetite and 500 g/Mg kerosene (the feed contained 27% Cr2O3). Slime tailings of Turkish Maadin Company, Kavak Chrome Concentrating Plant in Eskisehir, which contain fine chromite, serpentine and olivine, were also investigated. It was found that chromite could not be satisfactorily recovered from the original slime sample in the presence and absence of NaOl by using the magnetic carrier technology. Additional FTIR studies performed with the investigated minerals showed that NaOl adsorption on chromite was greater than that on serpentine and magnetite minerals. It was also found that NaOl adsorption on serpentine is significantly reduced in the presence of magnetite while it increases only slightly on chromite.

6

Dry magnetic separation of olivine sand

75%

Kleiv R. A. , Thornhill M.

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tom Vol. 47

213-228

EN

This paper investigates the potential for using dry magnetic separation to reduce the chromium content of a dried high quality olivine sand product in order to meet with anticipated future quality demands. The original feed contained 0.28-0.29% Cr2O3 of which approximately one third occurred as chromite and two thirds as chlorite. Two stage Permroll separation (at 0.50 T (max) and 0.92 T (max)) produced a concentrated product containing 0.13% Cr2O3 at a product recovery of 85.28%, thus reducing the chromium content by 55%. Some 80% of this reduction was achieved as a result of the first separation stage where chromite reported to the magnetic tailings at a recovery close to 100%. The chromium remaining in the concentrated product must be attributed to chlorite. Leachates obtained from leaching tests performed on the feed and the products were characterised by very low chromium concentrations, and the results suggest that chromium is more easily released from chlorite than chromite. This study shows that dry magnetic separation could be considered when a reduction of the chromium content of dried high quality olivine sand products is required.

7

Evaluation by Multi Gravity Separator (MGS) of a Low Grade Chromite Tailing From Yesilova-Burdur (Turkey)

63%

Deniz V.

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tom R. 21, nr 1/2

101--106

EN

In this study, concentrability by a Multi-Gravity-Separator (MGS) of the chromite tailings with content 23.84% Cr2O3 from Yeşilova-Burdur (Turkey) is investigated. Mineralogical analyses showed that the chromite tailings contain chromite and serpentine which formed as a result of alteration of serpantine group minerals such as olivines, chrysotile and talc. The tailings generated from chromite beneficiation plants in Turkey are generally concentrated by slime tables (Deister shaking tables) for producing the desirable saleable grade. However, slime tables are concentrating with low recovery for chromite minerals which are very fine particle size. MGS is an efficient method for separation of minerals by gravity at very fine particle size. In experimental studies, the effects of feed rate, washwater rate, drum speed and tilt angle, which are important for operating parameters of MGS observed for the low grade chromite tailings were investigated. As a result of the experimental studies performed, it was obtained a concentrate with saleable chromite grade and recovery from the tailings which is having size fraction under 0.075 mm.

PL

W artykule przedstawiono wzbogacalność w separatorze grawitacyjnym (MGS) odpadów chromitowych o zawartości 23,84% Cr2O3 z Yeşilova-Burdur (Turcja). Analizy mineralogiczne wykazały, że odpady chromitowe zawierają chromit i serpentyn, które powstały w wyniku zmian minerałów z grupy serpenitu, takich jak oliwiny, chryzolit i talk. Odpady wytwarzane w zakładach wzbogacania chromitu w Turcji są na ogół wzbogacanie na stołach koncentracyjnych dla drobnych ziaren (stoły wytrząsające Deister) w celu uzyskania produktu nadającego się do sprzedaży. Jednak stoły koncentracyjne się charakteryzują się z niskim uzyskiem minerałów chromitowych o drobnym uziarnieniu. MGS to skuteczna metoda wydzielania grawitacyjnego bardzo drobnych cząstek. W badaniach eksperymentalnych zbadano wpływ prędkości podawania, prędkości wody do wzbogacania, prędkości bębna i kąta pochylenia, które są ważne dla parametrów operacyjnych MGS badanych odpadów chromitowych niskiej jakości. W wyniku przeprowadzonych badań eksperymentalnych uzyskano z odpadów o uziarnieniu poniżej 0,075 mm koncentrat chromitu o jakości handlowej.

8

Badanie zróżnicowania składu chemicznego Cr spineli w obrębie masywu skał ultramaficznych na przykładzie SE Kosowa : zastosowanie w poszukiwaniach i wzbogacaniu rud chromu

63%

Ożóg M. , Pieczonka J. , Piestrzyński A. , Ćwiertnia T.

Przegląd Geologiczny

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2019

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tom Vol. 67, nr 3

186--188

EN

New data on chemistry of Cr spinels hosted within the ultramafic massif located in SE Kosovo show variations in their primary composition, which depends on ore and rock types. Spinels form disseminated and vein type ores and accessory spinels in peridotites are characterized by lower Cr and higher Fe concentrations in comparison to spinels making up massive ores. Concentrations of these metals increase in altered spinels both in ores and peridotites. Contents ofMn and Zn tend to be higher in accessory spinels than in spinels occurring in ores. The lower Cr:Fe ratio for Cr-rich spinels in disseminated ores in relations to chromite in massive ores may have an influence on their industrial usefulness. The use of EPMA-WDS technique for detrital spinels should be considered as an effective tool for chromium deposit exploration, especially in greenfield projects, to assess an ultramafic massifpotential for hosting rich ores. Chemical analyses of spinels are recommended in planning a beneficiation process for the low-grade chromite ores, in order to obtain high quality concentrates.

9

Porównanie metod klasycznych i nowoczesnej mikrofalowej wytwarzania rdzeni z mas ze szkłem wodnym

63%

Stachowicz M. , Granat K. , Małachowska A.

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2014

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tom Vol. 14, iss. 2 spec.

83--88

PL

W pracy przedstawiono wyniki porównania wybranych współczesnych metod produkcji rdzeni odlewniczych z mas formierskich ze szkłem wodnym sporządzonych na bazie osnowy kwarcowej i chromitowej. Masy formierskie z nieorganicznym spoiwem, jakim jest szkło wodne, są nieszkodliwe dla środowiska, neutralne dla ludzi i relatywnie tanie. Na tle tradycyjnych metod wykonywania rdzeni z mas ze szkłem wodnym: w procesie CO2, w technologii ciekłych estrów lub drogą tradycyjnego suszenia, innowacyjna metoda szybkiego utwardzania mikrofalami umożliwia ograniczenie ilości stosowanych materiałów, zmniejszenie wytrzymałości resztkowej masy, a tym samym poprawę jej wybijalności. W poniższej pracy zestawiono dostępne informacje na temat mikrofalowego procesu utwardzania mas zawierających szkło wodne, właściwości wytrzymałościowych zużytych mas kwarcowych i chromitowych, jak również porównanie kosztów praktycznego zastosowania tej technologii w warunkach pracującej rdzeniarni. Ponadto, wskazano korzyści wynikające z zastosowania tego innowacyjnego i przyjaznego dla środowiska rozwiązania, które może skutecznie zastąpić tradycyjne, często materiało- i energochłonne, procesy wytwarzania rdzeni z mas ze szkłem wodnym, sporządzanych z użyciem osnowy chromitowej lub kwarcowej.

EN

The paper presents examination results of different, modern casting core production methods of water-glass moulding sands based on silica or chromite sand matrixes. Those sandmixes are harmless for the environment, neutral for humans and relatively cheap. Against the background of traditional methods of core making such as CO2 process, liquid esters or traditional drying, the innovative method of rapid hardening by microwave heating permits restricting quantity of used materials, reduction of the residual strength and thus improves knock-out properties. In this paper, compiled is available information about microwave hardening of water-glass containing sandmixes, as well as residual strength properties of silica or chromite moulding sands, as well as a comparison of the costs of the practical application of this technology in the working foundry. In addition, some benefits are indicated, resulting from applying such an innovative and environment-friendly solution effectively replacing traditional, material and energy-consuming processes of preparing casting cores from water-glass containing moulding sands with chromite or silica matrixes.

10

Badanie aktywności chemicznej materiałów elektrodowych zawierających chromit lantanu.

51%

Róg G. , Kozłowska-Róg A. , Bućko M.

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1999

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tom R. 50, nr 4

27-31

PL

W oparciu o obliczone wartości zmian entalpii reakcji zachodzących między chromitami lantanowo-wapniowymi i dwutlenkiem cyrkonu stabilizowanym wapniem oraz reakcji chromitów lantanowo-wapniowych z tlenkiem węgla i wodorem, scharakteryzowano aktywność chemiczną otrzymanych materiałów elektrodowych La1-xCaxCrO3 (x większe lub równe od zera i mniejsze lub równe 0,4) względem innych materiałów powszechnie stosowanych w urządzeniach elektrochemicznych. Standardowe entalpie swobodne tworzenia dla produktów mogących powstawać na skutek przebiegu wymienionych reakcji wyznaczono metodą pomiaru siły elektromotorycznej (SEM) stałych ogniw galwanicznych. Stwierdzono, że w wyniku reakcji badanych materiałów z elektrolitem stałym, którym jest stabilizowany wapniem ZrO2, mogą tworzyć się cyrkoniany wapnia i lantanu, chromit wapnia oraz roztwory stałe tlenków chromu (III) i lantanu (III) w dwutlenku cyrkonu. Chromity lantanowo-wapniowe są natomiast odporne na redukujące działanie tlenku węgla i wodoru.

11

Mineralizacja kruszcowa w skałach ultramaficznych pasma Mnicha w zachodniej części masywu Braszowice–Brzeźnica (Dolny Śląsk)

51%

Sadłowska K.

Biuletyn Państwowego Instytutu Geologicznego

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2011

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tom nr 447

99--116

PL

Skały ultramaficzne masywu Braszowice–Brzeźnica to głównie harzburgity, dunity i lherzolity, które w różnym stopniu uległy serpentynizacji. Stanowią one wyższą część członu ultramaficznego sekwencji ofiolitu sudeckiego. Skały ultramaficzne sekwencji ofiolitowych są znane z wystąpień złóż: chromu, niklu, kobaltu oraz pierwiastków grupy platyny. W badanych skałach minerały kruszcowe to przede wszystkim tlenki: chromit, spinel Fe-Cr i magnetyt. Wśród siarczków dominują siarczki niklu i żelaza, różniące się między sobą proporcjami tych dwóch pierwiastków. Zidentyfikowane siarczki to: heazlewoodyt (Ni3S2), pentlandyt (Ni,Fe)9S8, milleryt (NiS) i godlewskit (Ni7S6). W siarczkach zidentyfikowano wrostki arsenków niklu. Minerały kruszcowe występują w formie rozproszonej, ich ziarna są ksenomorficzne, o zróżnicowanych rozmiarach od kilku µm do 4 mm. Pierwotne minerały kruszcowe – chromit, pentlandyt, pirotyn i chalkopiryt w procesie serpentynizacji uległy przemianom, w wyniku czego powstały wtórne minerały kruszczowe – spinel Fe-Cr, cztery generacje magnetytu, siarczki Ni-Fe oraz arsenki niklu. W czasie serpentynizacji ze struktury chromitu był odprowadzany Cr, Al, Mg, a w ich miejsce podstawiane było Fe. W wyniku tego procesu krystalizował ferrichromit i magnetyt Ia. Magnetyt Ib wykrystalizował w pseudomorfozach po oliwinach i piroksenach. W zaawansowanym stadium serpentynizacji krystalizował magnetyt II równocześnie z siarczkami.

EN

Ultramafic rocks of the Braszowice–Brzeznica massif consist of harzburgites, dunites and lherzolites that are serpentinised in various degree. These rocks are regard as upper part of ultramafic sequence of the Sudetic ophiolite complex. Ultramafic rocks of ophiolite sequences are often associated with important mineral deposits like chrome, nickel, cobalt and PGE. EPMA analyses show that the most aboundant ore minerals are oxides like chromite, ferrichromite, magnetite. Sulphide ore minerals are mainly Fe-Ni sulphides. Documented sulphides are: heazlewoodite (Ni3S2), pentlandite(Ni,Fe)9S8, millerite (NiS), godlevskite (Ni7S6). In some sulphide grains occur nickel arsenides inclusions. Ore mineral are dispersed, forms xenomorphic grains from several µm to 4 mm in size. Primary ore minerals like chromite, pentlandite, pyrrhotite and chalkopyrite were affected by fluids, which results in precipitation of secondary mineral phases: Fe-Cr spinel, four generations of magnetite, Fe-Ni sulphides and Ni arsenides. During serpentinisation Cr, Al, Mg in chromite strutcutre were replaced by Fe. Result of this alteration is Fe-Cr spinel and magnetite Ia. Magnetite Ib crystalized in pseudomorphs after olivines and pyroxenenes. Magnetite II precipitate simultaneously with sulphides.