SOLVENT EXTRACTION OF COBALT AND ZINC FROM SULPHATE
SOLUTIONS USING PHOSPHORIC, PHOSPHONIC AND PHOSPHINIC ACIDS
K.C. Nathsarma* and P.V.R. Bhaskara Sarma
Hydrometallurgy Division, Regional Research Laboratory
Bhubaneswar-751 013, Orissa, India
Received 10 April, 2002; accepted 15 February 2003
ABSTRACT
Extraction and separation of cobalt and zinc was studied from a sulphate solution using NaD2EHPA, NaPC88A and NaCyanex 272 of 0.04 M concentration. The percentage extraction and D
Zn
values increased with increasing equilibrium pH. Of the three extractants studied, NaD2EHPA was found to be the most suitable extractant for the separation of metal ions. Separation factor for cobalt and zinc increased with increasing equilibrium pH and was the highest (3394) at pH 5.65. Quantitative extraction (at equal phase ratio) and stripping (at
A:O=1:5) of zinc could be achieved in two counter-current stages. Between H
2
SO
4
solution and zinc spent electrolyte (containing the same concentration of H
2
SO
4
), the former was found to be a better stripping agent for zinc. Extraction (>99%) of cobalt could be achieved in two counter current stages at equal phase ratio and the metal could be stripped quantitatively in two counter-current stages from the loaded solvent with H
2
SO
4
solution of
2.0 kg/m
3
concentration.
Keywords : Solvent extraction, Cobalt, Zinc, D2EHPA, PC 88A, Cyanex 272 Countercurrent simulation
* nathsarma@rrlbhu.res.in
IMPACT CRUSHING APPROACH TO THE RELATIONSHIP OF
ENERGY AND PARTICLE SIZE IN COMMINUTION
E. Th. Stamboliadis
**
Department of Mineral Resources Engimeering, laboratory of Mineral Processing
Technical University of Crete

73100 Chania
Received 12 June, 2002; accepted 14 March 2003
ABSTRACT
The theories of Rittinger, Kick and Bond, that relate the energy required for comminution to the particle size of the feed and product do not provide for a size distribution of the material. The present theory tries to incorporate the concept of particle size distribution into the existing ones. Charles, firstly presented such an approach, but he used a different model of size reduction. He borrogh the model of Walker and Shaw according to which, the size of a particle is continuously reduced to an infinetly smaller particle at a time. The present model accepts that breakage of a mother paricle produces more than one daughter particles, which have a certain size distribution.
The energy required to create each individual particle, by exposing all of its surface, is given by the formula: Q x
=(C
S
.S
x
) n or Q x
=(C
S
.f) n .x
2n where: x the size of the particle, S x the surface area, f the surface coefficient, while C
S
and n are constants >0. The specific energy
(energy per unit mass) for the same created particle is: q x
=(C
S
.f) n
.x
2n-3
/(k.ρ) where: ρ the particle density and k the volume coefficient. Assuming a GGS size distribution of the daughter particles, the energy required to produce an assembly of particles having a total mass W o
, size modulus y and distribution modulus α is:
E y
 k
(C
 ρ
S

 f) n

2n


α
3
 W
 α o

 y 2n  3
, for (2n-3+α )> 0 . In this case the laws of Rittinger and Bond are derived as partial cases for values of n equal to 1 and 1.25 respectively. For (2n-3+α) = 0 the energy is given by: E y

(C
S
 f) k n
 ρ
 W o  lny y a
α
Keywords :Crushing, comminution, particle size, energy
* elistach@mred.tuc.gr