الفهرس 
1.2. Metallurgical Methods for Leaching Metal Values from LowOnly 14 pages are availabe for public view
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Abstract
Several studies related to the exploration of Mn-Fe ore at Um Bogma formation,
Central Sinai indicated to the presence of some valuable metals in the host rock as a
result of mineralization. It mainly includes Mn, Cu, Ni, U …..etc. Development of the
methods required for leaching and recovery in addition of studying the kinetics of these
procedures is of great important. Actually, the choice of the suitable procedure for
leaching and recovery of each metal value depends on the concentration of each metal
and the contaminant impurities. Thereby, the present work is directed towards the
selective leaching and recovery of Mn, Cu and U species from a proper collected
manganese ore sample due to their useful industrial applications.
This work comprises three chapters; the first one includes the literature survey
reported for the extractive metallurgical processes of Mn ore materials. Also, the kinetics
studies of Mn leaching have been briefly reviewed. The second chapter deals with the
experimental work including the optimum leaching, extraction and recovery procedures
as well as the chemicals and apparatus used during the course of work. The third chapter
involves the results and discussions of the obtained data. It also includes, the kinetic
reduction leaching of Mn using sodium sulfite or malonic acid as reductant. Finally, a
workable flow sheet comprises the all steps involving these processes is presented.
To realize the objectives of this work a representative sample assaying 32.6%
MnO2 from Alloga localitie at Um Bogma, Sinai was collected. Chemical analysis of the
sample indicates the relatively high iron oxides as well as CaO, MgO and alumina while
copper and uranium content amounted to 1.7% and 0.0071% respectively. The X-ray
diffraction analysis revealed to the presence of cryptomelane (KMn8O16), hematite
(Fe2O3), quartz (SiO2), albite (NaAlSi3O8) and paratacamite Cu2(OH)3Cl minerals.
Therefore, acid leaching was designed to dissolve the interested metal values
(manganese, copper, uranium) in presence of suitable reductant. Malonic acid and
sodium sulfite were used as reductants in sulfuric acid medium. The relevant leaching factors optimized at 1.5M H2SO4 and 14% Na2SO3 for 90
minutes at 80ºC in a solid liquid ratio of 1:10 in the presence of sodium sulfite as a
reductant, from this study it has been revealed that 97% of Mn, 99.9%U, and 90.5% Cu
leaching efficiency have been realized together with 9.3% iron dissolution.
Using malonic acid as reductant, several experiments have been performed to
study the relevant leaching parameters. The latter have thus been optimized as 1M H2SO4
in presence of 9% malonic acid in a solid/liquid ratio of 1:10 for 90 minutes leaching
time at 80ºC and using an ore ground to -74 μm grain size. Under these conditions the
leaching efficiencies of manganese, copper and uranium have attained 96.5%, 92% and
98% respectively together with iron dissolution 14%.
To recovery of the dissolved manganese, copper and uranium metal values a
proper slufate leach liquor has been prepared at optimum conditions. Ion exchange
procedure was suggested for recovery of U due to its relatively low concentration.
However, solvent extraction technique has been applied for Mn and Cu recovery.
Amberlite IRA 400 resin was used for adsorption and separation of uranium from sulfate
leach liquor with flow rate 1.2 ml/ minute. The total U adsorption efficiency was
94.78 %. Uranium was then eluted from the resin by 1M NaCl acidified to 0.1M sulfuric
acid using a contact time of 1.6 ml /min. The elution efficiency of 99 % has been
realized. Uranium from the collected eluate was precipitated at a pH of about 6.5 using
40 % NH4OH solution in the form of ammonium diuranate.
To recover copper species a solvent extraction procedure was proposed using LIX-
84 as a selective extractant from the sulfate solution. The aqueous solution was adjusted
to pH 2.3 and shook with 5% LIX 84 in kerosene at organic / aqueous phase ratio = 1/1
for 5 minutes with extraction efficiency of about 99.1 %. Copper ions was stripped from
loaded LIX 84 extractant, by 10% sulfuric acid to get pure copper sulfate solution at
organic / aqueous phase ratio = 1/1 for 5 minutes with stripping efficiency of about 99 %.
Copper species was precipitated by ammonia solution at pH = 5.5 to yield of Cu (OH)2
precipitate which ignited at 1000° C to produce CuO product. The Cu and U free liquor is then directed to the second solvent extraction of Mn
using D2EHPA. To realize this object the aqueous solution was adjusted to pH 2.5 and
shook with 20% v/v of D2EHPA in kerosene at organic /aqueous ratio (O/A) =1/1 at
room temperature for 30 minutes of contact. The extraction efficiency of Mn was
attained about 95.65 %. Manganese species was stripped from loaded D2EHPA, by 4M
sulfuric acid to get pure manganese sulfate solution at organic / aqueous phase ratio =
1/0.5 at room temperature for 15 minutes of contact with stripping efficiency of about 98
%. Manganese ions was precipitated by sodium hydroxide solution at pH = 10 to yield of
Mn (OH)2 precipitate which ignite at 1000°C to produce Bixbyite Mn2O3 (black)
product. It has also been possible to produce hausmannite (Mn3O4) by addition of H2O2
to Mn (OH)2 with continuous stirring. Finally, a workable flow sheet describing all the
studied procedures for the processing of studied ore material has been proposed.
The leaching kinetics of the dissolved manganese cations of the studied sample
using H2SO4 in presence of Na2SO3 and malonic acid showed that the leaching rate of
manganese species is controlled by diffusion through the ‘‘product’’ layer. As a matter
of fact, the leaching rate of both set experiments followed the kinetic model 1 – 2/3(X) –
(1-X)2/3 = kt with an apparent activation energy of 28.37, 29.61 kJ/mole respectively.
Similarly, the results of the kinetics study showed that both H2SO4 and Na2SO3, malonic
acid reductants concentrations as well as temperature are the main factors influencing the
leaching processes. from these results, a reaction order of 2.63 for total H2SO4
concentration has been indicated. On the other hand, the leaching rate was found to
depend strongly on the Na2SO3 concentration where a reaction order of 3.7 has been
obtained. A reaction order of 1.58 for total H2SO4 concentration has been revealed using
malonic acid.