Download A. M. Zayed1 BENEFICIATION OF AKTAS QUARTZ DEPOSITS

A. M. Zayed1
BENEFICIATION OF AKTAS QUARTZ DEPOSITS, CENTRAL KAZAKHSTAN,
FOR HI-TECH INDUSTRIES
The demand for the raw material quartz is increasing worldwide, in particular, the demand for
high-purity quartz (HPQ; e.g. [1,2]). Therefore, quartz has been recently considered as a strategic mineral
because it represents the raw material for special applications in high-tech industry. The trace-element
contents of quartz are its most important quality criteria. Quartz is designated high purity when it contains
less than 50 ?g g−1 of [3], which mainly comprise structurally bound trace elements (B, Li, Al, Ge, Ti, Fe,
Mn, Ca, K, Na and P) in the quartz lattice, also micro-inclusions of minerals and trapped fluids. Al and Ti
besides Li, P and B are used as indicators of the quality of the quartz. These elements are important
quality-determining trace elements depending on the industrial application being considered for the raw
material. High Ti concentrations, for example, change the absorption behavior of optical silica glass.
Metallic silicon and polysilicon are bred in quartz crucibles, and high P and B concentration in the quartz
glass of the crucibles contaminates the growing silicon crystals, which are used for solar cells or computer
chips. Moreover, Al, Ti and Li are difficult to remove during refinement of quartz. Therefore, the industry
is highly interested in quartz resources with low initial trace-element concentrations to lower production
costs and to improve the quality of the quartz products. But when these resources are not available,
affordable industrial dressing becomes a necessity [4].
Kazakhstan is considered as a major province of quartz raw materials. In the territory of the
republic there are large and widespread usable quartz raw material deposits of high geological and
genetical types. Plutonogenic-metamorphgenic quartz veins and metasomatic types (quartzites) are most
frequent in Central Kazakhstan. Quartz pegmatites are in the East, Central, Southern and Western
Kazakhstan [5].
All these quartz deposits, unfortunately, have not been studied in detail for their suitability for hitech industries and they are waiting for their turn to be studied. Therefore, the quartz deposits of Aktas
were evaluated after carrying out some beneficiation processes to measure their compatibility for hi-tech
industries.
Methods and Techniques
The methods and techniques that have been applied on the Akatas quartz deposits are: 1)
Geochemical analyses by using the XRF techniques and 2) Beneficiation processes by froth Floatation in
three stages. These stages were carried out at a fixed pH condition (5.5 - 6) but with changing in the time
of grinding (20, 40, 60 Min, respectively).
The geochemical analyses by using the XRF technique were carried out in the Laboratory of
Continental Dynamics of Northwestern University (China). Beneficiation processes were carried out in
the laboratory of the Center of Earth Sciences, Metallurgy and Beneficiation (Kazakhstan).
Beneficiation processes of Aktas quartz deposits
The processing technologies have to be adapted for specific requirements of quartz raw materials.
Only in the rarest instances, it is possible to use raw materials right away without some prior processing.
Processing technologies therefore, play a central role in the value enhancement chain and maximum
utilization of quartz. These technologies are the decisive factor in the commercial success of a deposit.
Process development always starts out from chemical and physical characteristics of natural quartz. In the
past, special attention was devoted to the development of the processes regarding sample preparation and
procedures for the detection of trace impurities in quartz up to the ppb-area[6]. Laboratory tests must be
done to figure out which process combination will lead to an optimal result at the end.
Froth Floatation process
The beneficiation processes that applied on the studied quartz samples of Aktas to remove the
excess and undesirable high contents of mineral inclusions (hematite, pyrite and magnetite) and
impurities (Fe2O3, TiO2, Al2O3, CaO ...etc) are froth Floatation in 3 stages at a fixed pH condition (5.5 6) but with changing in the time of grinding (20, 40, 60 Min to 74 micron, respectively).
The resulted concentrates of Floatation were subjected to chemical analyses by XRF. The analyses
results are given in table 1.
Devices used:
Russian Floatation device FML of speed 1200 turns/ Minute, pH Meter Device.
Floatation steps:
The froth Floatation that carried out on the quartz deposits of Aktas are divided into two parts,
Main Floatation and control Flotation. Before the main Flotation, grinding was conducted in the presence
of sodium sulphide, Na2S (100 g/t). During the main Flotation the following chemicals were used:
- Sulfuric acid (H2SO4) for adjusting the pH condition around 5.5-6.0 (70 g/t);
- Sodium silicate (Nа2SiO3) for quartz depression (200 g/t);
- Collectors - oleic acid and butyl xanthate (150 g/t);
- Foaming agent - T-66 (60 g/t).
Also during the control Flotation the following chemicals were used:
- Sulfuric acid (H2SO4) for adjusting the pH condition around 5.5-6.0 (20 g/t);
- Collectors - oleic acid and butyl xanthate (50 g/t);
- Foaming agent - T-66 (30 g/t).
Table 1. The results of froth Flotation of the quartz deposits of Aktas
Sample №
Concentrate
Tails1
Tails2
SiO2
TiO2
A12O3
Fe2O3T
MnO
MgO
CaO
Na2O
K2O
P2O5
L.O.I
Wt%
Wt gm
Wt%
Wt gm
Wt%
Wt gm
Before Floatation
After Floatation
Aktas
Stage1
Stage 2
Stage 3
71.8
80.56
88.89
3.59
411.5
451.1
6.91
8.38
5.3
34.6
42.8
26.9
21.81
11.06
5.81
109.1
56.5
29.5
Major oxides (wt%)
99.29
99.60
98.71
98.83
<0.01
<0.01
<0.01
< 0.01
0.03
0.02
0.01
0.02
0.16
0.11
0.58
0.79
<0.01
<0.01
<0.01
< 0.01
<0.01
<0.01
<0.01
< 0.01
0.05
0.03
0.05
0.04
0.02
0.02
0.01
0.01
0.01
0.01
<0.01
<0.01
0.01
0.01
0.01
0.01
0.26
0.23
0.35
0.36
As shown in table 1, the beneficiation of Aktas quartz deposits with froth Floatation in the 1st stage
(20 Min time of grinding) displayed a marked increase in the SiO2 content (from 99.29 before Floatation
to 99.60 % after Floatation) and minimized the A12O3 (from 0.03 before Floatation to 0.02 % after
Floatation), Fe2O3 (from 0.16 before Floatation to 0.11 % after Floatation) and CaO (from 0.05 before
Floatation to 0.03 % after Floatation) contents to a noticeable percent, while the 2nd and 3rd stages of
Floatation had a negative effect on the quartz and this is reflected by the decrease of SiO2 content (98.71
% in the 2nd stage and 98.83% in the 3rd stage of Floatation) and increase of Fe2O3 content (0.58 % in the
2nd stage and 0.79% in the 3rd stage of Floatation), hence it is recommended to use the 1st stage of
Floatation (grinding time 20 Min and the pH 5.5-6) because it gives better results.
Discussion
The geochemical analyses that carried out on the quartz deposits of Aktas revealed that they can be
classified as pure quartz owning to their high silica content, which ranges from 99.26 - 99.29 % with an
average content 99.27%. Also they are characterized by low contents of Al2O3, Fe2O3, CaO, MgO, Na2O,
K2O and P2O5.
The beneficiation processes that carried out on the quartz deposits of Aktas to remove the excess
and undesirable high contents of mineral inclusions (hematite, pyrite and magnetite) and impurities
(Fe2O3, TiO2, Al2O3, CaO ...etc) are froth Floatation in three stages. These stages were carried out at a
fixed pH condition (5.5 - 6) but with changing in the time of grinding (20, 40, 60 Min, respectively).
The first stage of froth Floatation that carried out on Aktas quartz deposits (pH condition (5.5 - 6)
and 20 Min time of grinding) has proved its efficiency and resulted in a marked increase in the SiO2
content and a decrease in the A12O3, Fe2O3 and CaO contents to a noticeable percent, while the 2nd and
the 3rd stages of Floatation (pH condition (5.5 - 6) and 40 and 60Min time of grinding, respectively) have
proved their inefficiency and displayed a negative effect on the quartz deposits of Aktas and this is
reflected by the decrease of SiO2 content and increase of Fe2O3 content.
The first stage of froth Floatation has qualified the quartz deposits of Aktas to be used for the production of
silicon carbide (SiO2 (99.50 to 99.75%), Al2O3 (0.04 to 0.05%), Fe2O3 (0.05 to 0.1%) and CaO+ MgO ≈1.1%
[7]).
Conclusion
The high degree of purity of the quartz deposits of Aktas has nominated and qualified these
deposits, even without beneficiation, to be used in hi-tech industries such as Aluminum alloy and
Ferrosilicon alloy industries.
The beneficiation processes with froth Floatation at a fixed condition (pH(5,5 - 6) and 20 Min time
of grinding) have qualified the quartz deposits of Aktas to be used for the production of silicon carbide.
REFERENCES
1. Moore, P., 2005. High-purity quartz. Ind Miner. 455, 53–57.
2. Haus, R., 2005. High demands on high purity. Ind Miner. 10, 62–67.
3. Muller, A., Ihlen, P. M., Wanvik, J. E., Flem, B., 2007. High-purity quartz mineralization in kyanite
quartzites. Miner. Deposita, Norway 42, 523–535.
4. Larsen, R.B., Polve M., Juve, G., 2000. GRANITE PEGMATITE QUARTZ FROM EVJE- JVELAND, TRACE ELEMENT
CHEMISTRY AND IMPLICATIONS FOR THE FORMATION OF HIGH-PURITY QUARTZ. Norges geologiske undersokelse Bulletin 436, 5765.
5. Мельников Е. П.,1988. Геология, генезис и промышленные типы месторождений кварца. Москва:
Недра, 260 с.
6. Dorfner-Anzaplan-Consulting-Processing technologies, Germany. (2010, April). Chemical 6. Retrieved
June 23, 2010, from HTTP:// www.anzaplan.de/index.cfm.
7. Psranawant, Germany. (2007, April), Product data sheet. Retrieved April 27, 2010, from
HTTP:// www.Psranawant.org.
Резюме
Обогащение, которое применяется на кварцевом сырье для удаления избыточного и нежелательного
содержания минеральных включений (гематит, пирит и магнетит), в том числе и примесей (Fe2Оз, TiO2,
Al2O3, CaO ... и т.д.), осуществляется в 3 опыта пеной флотации при фиксированной среде рН (5.5 - 6), но с
измельчением и промежуточным изменением времени (20, 40, 60 мин, соответственно).
Обогащение кварца месторождения Актас с пенной флотацией в 1-й опыте проявило заметно
увеличение содержания SiO2 и понижение содержание А12О3, Fe2O3 и СаО. Во втором и третьем опыте
флотации было проявлено негативное влияние на кварц. Об этом свидетельствует уменьшение содержания
SiO2 (98.71% во 2-м опыте, 98.83% в 3-м опыте флотации соответственно) и повышение содержания Fe2O3
(0.58% во 2-м этапе, 0.79% в 3-м опыте флотации соответственно). Поэтому рекомендуется использовать
первый опыт флотации (20 мин, рН 5,5-6), при котором получены положительные результаты.
Summary
The beneficiation processes that applied on the studied quartz deposits of Aktas to remove the excess and
undesirable high contents of mineral inclusions (hematite, pyrite and magnetite) and impurities (Fe2O3, TiO2, Al2O3,
CaO ...etc) are froth Floatation in three stages. These stages were carried out at a fixed pH condition (5.5 - 6) but
with changing the time of grinding (20, 40, 60 Min, respectively).
The beneficiation of Aktas quartz deposits with froth Floatation in the 1st stage (20 Min time of grinding)
displayed a marked increase in the SiO2 content and minimized the A12O3, Fe2O3 and CaO contents to a noticeable
percent, while the 2nd and 3rd stages of Floatation had a negative effect on the quartz and this is reflected by the
decrease of SiO2 content (98.71 % in the 2nd stage and 98.83% in the 3rd stage of Floatation) and increase of Fe2O3
content (0.58 % in the 2nd stage and 0.79% in the 3rd stage of Floatation), hence it is recommended to use the 1st
stage of Floatation (grinding time 20 Min and the pH 5.5-6) because it gives better results.
The beneficiation processes with froth Floatation at a fixed condition (pH(5,5 - 6) and 20 Min time of
grinding) have qualified the quartz deposits of Aktas to be used for the production of silicon carbide.
Key words: Mineral inclusions and impurities, froth Floatation, hi-tech industries, silicon carbide
Introduction
КазНТУ им. К.И. Сатпаева
Поступила 8.04.11