Metal oxide, acid-soluble iron and arsenate equilibrium pH ө Acid dissolution reaction Balance standard pH ө SnO 2 +4H + ====Sn 4+ +2H 2 O -2.102 -2.895 -3.55 Cu 2 O+2H + === 2Cu + +H 2 O -0.8395 1.921 　 Fe 2 O 3 +6H + ====2Fe 3+ +3H 2 O -0.24 -0.9998 -1.579 Ga 2 O 3 +6H + ===2Ga 3+ +3H 2 O 0.743 　 -1.412 Fe 3 O 4 +8H + ===2Fe 3+ +Fe 2+ +4H 2 O 0.891 0.043 　 In 2 O 3 +6H + ====2In 3+ +3H 2 O 2.522 0.969 -0.453 CuO+2H + === Cu 2+ +H 2 O 3.945 3.549 1.78 ZnO+2H + === Zn 2+ +H 2 O 5.801 4.374 2.88 NiO+2H + === Ni 2+ +H 2 O 6.06 3.162 2.58 CoO+2H + === Co 2+ +H 2 O 7.51 5.5809 3.89 CdO+2H + === Cd 2+ + H 2 O 8.69 　 　 MnO+2H + === Mn 2+ +H 2 O 8.98 6.7921 　 ZnO · Fe 2 O 3 +8H + === Zn 2+ +2Fe 3+ +4H 2 O 0.6747 -0.1524 　 NiO · Fe 2 O 3 +8H + === Ni 2+ +2Fe 3+ +4H 2 O 1.227 0.205 　 CoO · Fe 2 O 3 +8H + === Co 2+ +2Fe 3+ +4H 2 O 1.213 0.305 　 CuO · Fe 2 O 3 +8H + === Cu 2+ +2Fe 3+ +4H 2 O 1.581 0.56 　 FeAsO 4 +3H + === Fe 3+ +H 3 AsO 4 1.027 0.1921 -0.511 Cu 3 ( AsO 4 ) 2 +6H + === 3Cu 2+ +2H 3 AsO 4 1.918 1.32 　 Zn 3 ( AsO 4 ) 2 +6H + === 3Zn 2+ +2H 3 AsO 4 3.294 2.441 　 Co 3 ( AsO 4 ) 2 +6H + === 3Co 2+ +2H 3 AsO 4 3.162 2.382 　 PbSiO 3 +2H + === Pb 2+ +H 2 SiO 3 2.86 　 　 FeO · SiO 2 +2H + === Fe 2+ +H 2 SiO 3 2.63 　 　 ZnO · SiO 2 +2H + === Zn 2+ +H 2 SiO 3 1.791 　 　 From the pH 上 in the above table, we can see the following rules: Main reaction equilibrium formula and E-pH diagram relationship in ZnS-H 2 O system sequence  number Reaction equilibrium E-pH relationship 1 O 2 +4H + +4e === 2H 2 O E=1.229-0.0591pH+0.01491gP o2 2 H + +2e === H 2 E=-0.0591 pH-0.02951gP H2 3 Zn 2+ +S+2e === ZnS E=0.264+0.02951g[Zn 2+ ] 4 ZnS+2H + === Zn 2+ +H 2 S ( g ) pH=-1.586-0.51g[Zn 2+ ]0.51gP H2S 5 S+2H + +2e === H 2 S ( g ) E=0.171-0.0591pH-0.02951 gP H2S 6 SO 4 2- +H + === HSO 4 - pH=1.91+1g[SO 4 2- ]0.51g[HSO 4 - ] 7 Zn 2+ +2e === Zn E=-0.763+0.02951g[Zn 2+ ] 8 ZnS+2H + +2e === Zn+H 2 S ( g ) E=-0.857-0.0591pH-0.02951gP H2S 9 HS - +H + === H 2 S ( g ) pH=8.00+lg[HS - ]-lgP H2S 10 S 2- +H + === HS - pH=12.9+lg[S 2- ]-lg[HS - ] 11 ZnS+2e === Zn+S 2- E=-1.474-0.02951lg[S 2- ] 12 Zn 2+ +2H 2 O === ZnO 2 2- +4H + pH=10.08-0.251g[Zn 2+ ]0.25lg[ZnO 2 2- ] The ZnS-H 20 O-pH diagram (bottom) can be drawn from the equilibrium in the table. The granulator machine can make granules from wet powder materials or break down the dry lumpish material, which is widely used by the industries of pharmacy, chemical and foodstuff. By driving of mechanism, the cylinderis swinging to-and-fro to force the target material squeezed from sieveto make out granules or to smash it as granules. This granulation machine is made of stainless steel, in line with GMP standards. Granulator Machine,Pelletizer machine,Pelletizing Machine,Dry Granulator,Granulation Machine JIANGYIN CITY XUAN TENG MACHINERY EQUIPMENT CO.,LTD , https://www.xuantengmixer.com
[next]
(1) The order of stability of the metal oxide in the acidic solution is: Sn0 2 >Cu 2 0>Fe 2 0 3 >Ga 2 0 3 >Fe 3 0 4 >In 2 0 3 >Cu0>Zn0>NiO> Coo>CdO>MnO. Since iron oxide is difficult to dissolve, separation of Mn, Cd, Co, Ni, Zn, Cu and iron can be achieved under normal pressure at a temperature of 25 to 100 ° C and a pH of 1 to 1.5.
(2) The order of stability of the ferrite in the metal in an acidic solution is:
Zn0·Fe 2 0 3 >NiO·Fe 2 0 3 >CoO·Fe 2 0 3 >Cu0·Fe 2 0 3
(3) The order of stability of the metal arsenate in an acidic solution is:
FeAs0 4 >Cu 3 (As0 4 ) 2 >Co 3 (As0 4 ) 2 >Zn 3 (As0 4 ) 2
(4) The order of stability of the metal silicate in an acidic solution is:
PbSi0 3 >FeSi0 3 >ZnSi0 3
(5) The order of stability of metal compounds such as zinc , copper , and diamonds is:
Ferrite>silicate>arsenate>oxide
(6) The pH of all oxides, ferrites, and arsenates. Both decrease with increasing temperature, which requires leaching at higher acidity.
Study on the leaching thermodynamics of zinc sulfide concentrates . The reaction of zinc sulfide (ZnS) and other metal sulfides in aqueous solution, what kind of substance will be formed at a certain pH and a certain potential, E-pH diagram can be used to study the reaction of MeS in aqueous solution. Thermodynamic law.
The main reaction equilibrium and E-pH diagrams in the ZnS-H 2 0 system are shown in the table below. [next]
It can be seen from the figure that there is a stable region of elemental sulfur. When the potential drops, pH value in the range 1.9-8, SO 4 2- reduced to elemental sulfur, and further reduced when the potential of pH <7, is further reduced to H 2 S, pH> further reduced to the HS when 7-- .
When the potential is raised, at pH<8, both H 2 S and HS − are oxidized to elemental sulfur S and then oxidized to SO 4 2- . At pH >8, HS − can be directly oxidized to SO 4 2- .