95 BEHAVIOR OF ANTIMONY AND ARSENIC IN SULFURIC ACID SOLUTION ABSTRACT CHOKO TEREZA ITO 1 TADAHISA NISHIMURA KASUTERU TOZAWA 1 The presence of antimony and arsenic in many mineral sulfides leads to a need to understand the way in which both species react in those processes which have been developed for extracting valuable elements from those minerals. This paper deals particular with the precipitation reactions of antimonious, antimonic, arsenious and arsenic species in sulfuric acid solution in relation to various hydranetàllurgical processes. The system Sb 2 0 (x:3,5) - As 2 o (y:3,5) - so 3 -H 2 o has been investigated a wide range Óf sulfuric ac1d concentration. The solubility and stability ranges of Sb20 3 , Sb 2 o 5 , As 2 o 3 aad compounds formed in the system have been deEermineà at 25 C. Furthermore, the behavior of antimony and arsenic in sulfuric acid solution is discussed. 1 Research Institute of Mineral Dressing and Metallurgy (SENKEN) Tohoku University Sendai, Japan
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95
BEHAVIOR OF ANTIMONY AND ARSENIC IN SULFURIC ACID SOLUTION
ABSTRACT
CHOKO TEREZA ITO 1
TADAHISA NISHIMURA KASUTERU TOZAWA 1
The presence of antimony and arsenic in many mineral sulfides leads to a need to understand the way in which both species react in those processes which have been developed for extracting valuable elements from those minerals.
This paper deals セョ@ particular with the precipitation reactions of antimonious, antimonic, arsenious and arsenic species in sulfuric acid solution in relation to various hydranetàllurgical processes.
The system Sb20 (x:3,5) - As 2o (y:3,5) - so3-H2o has been investigated ッカセイ@ a wide range Óf sulfuric ac1d concentration. The solubility and stability ranges of Sb203 , Sb2o5 , As 2o3 aad compounds formed in the system have been deEermineà at 25 C. Furthermore, the behavior of antimony and arsenic in sulfuric acid solution is discussed.
1 Research Institute of Mineral Dressing and Metallurgy (SENKEN) Tohoku University Sendai, Japan
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BEHAVIOR OF ANTIMONY AND ARSENIC IN SULFURIC ACID SOLUTION
by Choko Tereza Ito, Tadahisa Nishimura
and Kazuteru Tozawa
Research Institute of Mineral Dressing
and Metallurgy (SENKEN)
Tohoku University
Sendai, Japan
ABSTRACT
The presence of antimony and arsenic in many mineral sulfides
leads to a need to understand the way in which both species react
in tho se processes which have been developed for extracting
valuable elements from those minerals.
This paper deals in particular with the precipitation reactions
of antimonious, antimonic, arsenious and arsenic species in
sulfuric acid solution in relation to various hydrometallurgi cal
processes.
The system, Sb 2ox ( x:3, 5 ) - As 20y ( y:3, 5 ) - so 3 - H20 has
been investigated over a wide ranges of sulfuric acid concentration.
The solubility and stability ranges of Sb 2o 3 , Sb 2o 5 , As 2o 3 and
compounds formed in the system have been determined at 25°C.
Furthermore, the behavior of antimony and arsenic in sulfuric acid
solution is discussed.
INTRODUCTION
ln copper smelters in Japan, various complex sulfide concentrates
are treated. An appreciable quantity of arsenic and antimony is
accompanied in the concentrates. Control of both elements is very
important for producing high grade copper metal. Many new processes
97
for their treatment have been developed and installed in some
smelters(1),(2), but there are still many problems to be solved.
Onahama 5melter(3) has been produced pure arsenic trioxide by
vacuum-cooling the filtrate of liquor( diluted sulfuric acid satu
rated with As 2o3 ) from plant for washing converter gas. It is very
important for production of pure arsenic trioxide to determine the
solubility of arsenic trioxide in concentrated sulfuric acid and to
examine the contamination with antimony.
Recently, arsenic and antimony contents tend to increase in a
conventional electrolyte for the electrorefining of copper. The
elements form often a floating slime which lowers the quality of
electrolytic copper(4).
To clarify the behavior of antimony and arsenic in sulfuric acid
solution for solving such problems in the hydrometallurgical opera-
tions, it is necessary to know the equilibrium for the following
systems.
( 1 ) The system 5b2o 3 - 503 - H20
(2) The system sb2o 5 - 5o3 - H20
(3) The system As 2o 3 - 5o3 - H2o
(4) The system As 2o 5 - 5o3 - H20
(5) The system 8b203 - As 2o 3 - 503 - H2o
(6) The system 5b2o 3 - As 2o 5 - 503 - H2o
(7) The system 5b2o 5 - As 2o 3 - so3 - H20
(8) The system sb2o 5 - As 2o 5 - so3 - H2o
In this paper, the equilibrium for these systems is investigated.
THE EQUILIBRIUM FOR THE SY5TEM Sb(III,V) - As(III,V) - S03 - H20
1. The system Sb20J - S03 - H20
H2o is of great interest in chemical
analytical procedures and in industry of production of various
98
antimony compounds. There is several information in the literature
on the system sb2o 3 - so3 - H2o.
fates are produced by reacting
A variety of antimony(III) sul-
Sb2o 3 and H2so4. The results
reported on the chemical compositinn and solubility of these com
pounds are inconsistent and contradictory.
The equilibrium for the system sb2o 3 - so3 - H2o was examined by
shaking the mixture of antimony trioxide and sulfuric acid solution
( O - 1820 g/1 H2so4 ) at 25°C for one month. The results from
the chemical analysis of solutions and precipitates are plotted
in Figure 1 together with data by Gospodinov et al. (5) at 100°C.
Various compounds are formed in the system Sb2o 3 - so3 - H2o at
both temperatures.
Figu r e 1(a) shows that the so3 /sb2o 3 molar ratio in the precipi
tates is either 0.50, 0.66, 1.0, 2.0 or 3 . 0, indicating the
existence of the five compounds. These compounds are represented
without indicating hydration as 2Sb2o 3 -so3 , 3Sb20 3 ·2S03, Sb203 •S03,
Sb2o 3 ·2so3 and Sb2o 3 ·3S03. At 25°C, Sb2o 3 is stable as a solid in
the range of O - 20 g/1 H2so4 , 2Sb2o 3 ·so3 in 30 - 360 g/1 H2so4 ,
3Sb 2o 3 ·2S0 3 in 400- 560 g/l H2 so 4 , Sb 2o 3·so 3 in 590- 880 g/1
H2so4 , Sb20 3 ·2S03 in 950 - 1280 g/1 H2so4 and Sb20 3 ·3S03 in 1370 -
1800 g/1 H2so4. Below 800 g/1 H2so4 , the results agree well with
those obtained at roem temperature by Hintermann et al.(6).
In Figure 1(b), Sb2o 3 -so3 and sb2o 3 ·2S03 have the highest so1u
bi1ity in 880 g/1 and in 1280 g/1 H2 so 4 at 25°C, respective1y.
Furthermore, the solubility of these compounds wi11 increase with
an increase in temperature.
The data of Figure 1 are a1so shown in Figure 2 as a ternary
diagram of the system sb2o 3 - so3 - H2o at 25°C. The typica1 X-ray
diffraction patterns of their compounds are shown in Figure 3.
99
2. The system 5b2o 5 - 503 - H2o
There is very little data on the system 5b 2o 5 - 50 3 - H2o.
The experiment was carried out by shaking the mixture of antimony
pentaoxide ( amorphous ) and sulfuric acid solution ( O - 1540 g/1
H25o4 ) at 25°C for one month. X-ray diffraction confirmed the
nonexistence of antimony(V) sulfate at 25°C. Figure 4 shows that
5b 2o 5 ( amorphous) is highly soluble at 1100 g/1 H25o 4 at 25°C.
3. The system As 2o 3 - 503 - H2o
The system As 2o 3 - 503 - H2o is of importance in many hydro
metallurgical processes for separation and recovery of arsenic as
arsenic trioxide from acidic solutions.
The equilibrium for this system was examined by shaking the mix-
ture of arsenic trioxide ( cubic and sulfuric acid solution ( O -
1770 g/1 H25o4 ) at 25°C for two weeks. X-ray diffraction confirmed
the existence of As 2o 3 and As 2o 3-5o 3 as a solid between O to 1550
at 25°C. The results proved the nonexistence of compounds of 5b2o 5
with As 2o 3 or As 2o 5 in sulfuric acid solution.
103
CONCLUSION
In arder to clarify the behavior of antimony and arsenie in
sulfurie aeid solution, the system sb2ox( x:3,5 )- As 2oy( y:3,5 )-
so3 - H2o át 25°C was investigated by mixing method. Six antimony
one arsenie sulfate in
the system As 2o 3 - so3 - H2o and one antimony arsenate and two
antimony arsenate sulfates in the system sb2o 3 - As 2o 5 - S03 - H20
were identified. The solubility and stability ranges of those
eornpounds, Sb2o 3 , Sb2o 5 and As 2o 3 were determined.
In production of arsenie trioxide from sulfurie aeid solution
eontaining a large amount of antirnony(III) by erystallization, the
produeed arsenie trioxide will be eontarninated with antimony(III)
beeause of very low solubility of antirnony(III) sulfates formed.
Only antimony(III) arsenates are formed as antirnony arsenie
eornpound in sulfurie aeid solution. Therefore, SbAs04 whieh is
stable below 900 g/1 H2so4 , is one of the eonstitutive eompounds
in the floating slirne during the eleetrorefining of eopper. To
further know distinetly the meehanism of formation of the floating
slirne, more detailed studies will also be neeessary in the presence
of bisrnuth and copper at higher temperature.
REFERENCES
(1) Mohri, E. : J. Min. Met. Inst. Japan, 94 451-456 (1978). (2) Yashuda, M. : J. Min. Met. Inst. Japan, W 555-560 (1984). (3) Kono, H., Sugawara, Y. and Hashimoto, M. : Paper presented at
112 th AIME Annual Meeting, Atlanta USA, Mareh 1983. (4) Lindsfrom, N.F.R. : Urlited States Patent, 3,753,877 (1973). (5) Gospodinov, G. and Ojkova, T. : z. anorg. allg. Chem., 472
233-240 (1981 ). (6) Hinterrnann, Jf.E. and Venuto, C.J.: J. Eleetroehern. Soe., 115
10-12 (1968). A -
(7) Menzies, A.W.C. and Potter, P.D. : J. Am. Chern. Soe., 34 1452 ( 1912). -
(8) Broul, M. et al. : Physieal Seiences Data 6, Solubility in Inorganie Two-Component Systems, Elsevier Seientific Publishirig Company (1981).
(9) Inornata, I. et al. : J. Sulphurie Aeid Soe., 9 127-133, 169-175 (1956). -