1 Metallurgy of Porphyry Copper- Gold-Molybdenum-Arsenic of Peru Eng. Enrique Echegaray Muniz 1 Manager CMPE Engineering S.A.C. Eng. César Ugarte Amaya 2 Sub /Manager CMPE Engineering S.A.C OVERVIEW The geological deposits of porphyry copper in the continents of America and Australasia, as well as in Peru, are distributed in mineralized belts. Locally in the Peru origin is as follows: Magmatic belt mineralized in copper - Moly's origin in the Paleocene at peruvian South. Mineralized Magmatic belt in copper - Moly's origin in the Eoceno-Oligoceno Skarn in mainly Apurimac at peruvian Center Magmatic Mineralized belt sulphides in secondary, primary copper-Moly-gold and arsenic's origin Mioceno at peruvian North Quality concentrates of copper and molybdenum in each of the three cases mentioned here, are just great secondary enrichment in copper (ranging from 28 to 38% of Cu) associations of different mineral contents of finely disseminated gold, silver, arsenic, bismuth, etc. which are payable additionally or have penalties in others with limitations of being received by the foundries. The design of the flow diagram for treatment of porphyry copper in each case is product of a meticulous work of research metallurgical in order support properly them engineering studies of feasibility that is comes performing for various mining projects. Only mentioned, without discussing them some planned routes of comprehensive treatment that includes the stage of processing of minerals such as: hydrometallurgical process, bio-leaching etc. which is working in stages of research and the scaling progressive to levels pilot and industrial. Each mineralization corresponds to a specific design of flow diagram in order to evaluate the economic sensitivity allowing the mining metallurgical project optimize.
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Metallurgy of Porphyry Copper- Gold-Molybdenum-Arsenic of Peru
300MMT to 4000MMT Medium to long 400MMT to 1800MMT
Medium to very long 400MMT to 4000MMT
Grade average
Copper 0.39 - 0.47% Cu 0.44 - 0.93% Cu 0.28 - 0.69% Cu Gold 0.03 g/t Au - 0.04.-0.25g/t Au 0.05-0.90g/t Au Silver 2.20-3.10 g/t Ag 1.45-4.75 g/t Ag 1.24-6.90 g/t Ag Moly 200 ppm Mo 130-300 ppm Mo About 100 ppm Mo Arsenic 11ppm As 240 to 7300ppm 500 ppm
Weathering Intense development of oxidos between 0 to 150 m and secondary sulfide in vertical zone
Limited Limited
Geometry Grouping of medium to large porphyry. Mineralization in intrusive or in covering rock...
Mineralized in Skarn complexes are small to medium-sized and irregular, or also under the intrusive porphyry, gold mineralization takes place also.
Structurally aligned porphyry. Mineralization occurs in the intrusive also as in the lining. Gold mineralization in the sandstones and tonnage, often associated with polymetallic Skarn in
Source: Copper in Peru: J. ACOSTA, A. BUSTAMANTE & m. CARDOZO. Or f INGEMMET , 31 ° PERUMIN 2013
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Chemical Composition and Reservations
Twenty projects in list, porphyry copper which are progressively being developed:
interchangeably in each area of the three mineralized belts, increasingly happens to free for
the engineering of the designer trends require further elaboration processes metallurgical
mining by the following aspects:
Lithologic domains of geo-metallurgical competition
Chemical composition of ores of Cu-Mo - Au-Ag and associated gang As-Fe - Al - Si
Table 2. Project 2016 for mineralized porphyry of Peru copper belts
South Zone Central Zone
North Zone
Quellaveco
0.57% Cu, 0.023%Mo,2.3Ag g/t
916 MT, Sulf
The Chancas
0.623% Cu, 0.049%Mo, 0.24 Au g/t 482MTS
Galen
0.52%Cu, 0.013%Mo,0.15 Au g/t
661 M
0.94% Cu 0.014% Mo, 1.7Ag g/t
213 MT, Oxy.
0.49% Cu, 0.03% Mo, 0.04 Au g/t
128MT Or 0.017% as, 4.76 Ag g/t
Zafranal 0.36%Cu 557 MT S Magistral 0.51 %Cu,0.06% Mo 270 MT Conga
0.28%Cu, 0.75 Au g/t
641 MT
Tia Maria 0.39%Cu 640 MT OXI Rondoni
0.3 - 0.5% Cu, 0. 43Ag oz/t 50 MT S Farm
0.69%Cu,2.4 Ag g/t
544MT
Cerro Verde II
0.49% Cu, 0.25% Mo 3400 S MT
Quechua 0.38% Cu, % Mo 680 MT Cañariaco
0.49% Cu
752 MT
0.2-0.5% Cu 232 MT Or
The Chankas 0.41% Cu,0.21% Mo 2, 316MT S Haquira
0.54%Cu, 130 ppm Mo 452MTS
River white
0.57%Cu, 228 ppm Mo
498 METERS
0.51%Cu, 178MT Or
…….
Mina Justa 0.79%Cu 413 MT Sand
0.29%Cu, 0.24 Au g/t
312 METERS
0.46 Au g/t 100MT
…….
Trapiche 0.487% Cu 449 MT Michiquillay
0.69%Cu,
544MT
Antilla 0.47% Cu, 0.009% Mo 154 MT
Massive deposits of copper are not included
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Stages of selective separation from concentrated bulk
Lower content of oxides of copper SX-EW
Greater occurrence of sulphide with secondary enrichment of copper or soluble in CN-
Requirement of metallurgical studies in samples by variability of recovery
Economic sensitivity of the contents and value of recoverable metals and disposal of tailings
project.
Superimposing the two figures following an on another of those two typical joined sections, which
allow you to see is there a rear upper area with higher content of copper oxide and Arsenic located
in lithologic of sericitic quartz that justify the crushing and agglomeration for lixiviation on heaps .
Instead an area of transition are to the side half left with a great range of copper grade around
sulfides of copper of 0.7%Cu justify another plant of concentration by flotation of sulphides that
requires focus two concentrated: one of greater tonnage with low law of As and high law of Cu and
another of less tonnage with high As and less content of copper for the hydrometallurgical route .
He stumps to be a first mined the supergene area with oxides of copper in shortest time and then
the area of secondary enrichment more the transition hypo gene ore a longer operational life of
mine.
NORTH MINERALIZED BELT: SECTION TYPICAL CHEMISTRY OF COPPER 1YCOMPOSICION
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North Mineralized belt: typical section 1 and its location Or N lithologic
3.0 GEOMETALLURGY: LITHOLOGICAL COMPETITION
In the review of comparative competition lithological existing plants and some recent in Peru
projects, (see table 3), it has a wide range in UCS (unconfined compressive strength)
approximately between 250 to 30 megapascals, for example between the lavas andesitic and
the dacitic silicification and the strong sulfides Intergrowth how thin veinlets or nodules that
there in the rocks of the Condestable mine hand on the other hand sandstone and quartzite of
the high river sand project show to be less competent. The examples mentioned include the
requirement to apply using the schema of fracturing of particles by high pressure rollers - ball
for rocks from moderately competent Mills; both belts of porphyry in the South and Central.
Instead is sees in examples of the girdle North that the scheme of mill SAG-with support of
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better planning of detonators of break by blasting in mine or post crushing of pebbles is
required, all this in seeks of a lower cost operating.
TABLE 3. BENCH MARKING OF OPERATIONS AND PROJECTS PER U
4.0 Soluble material content of minerals
TABLE 4 THICKNESS OF OXIDES AND SECONDARY, PRIMARY, SULPHIDES ZONE NORTH
Taladrom. Lithology pH % Cu
% Cu Ac.
% Cu, CN
% Cu Residual sulfur
Specific gravity
62 to 100 Sandstone Ore Primary type SST-PR
4.4 0.53 0.04 0.15 0.31 2.63
18 to 67.3 Dacite Ore Secondary PD1-SS
5.4 1.09 0.14 0.85 0.07 2.68
130 to 188 Sandstone Ore Secondary SST-SS
5.7 0.92 0.09 0.47 0.33 2.70
208 to 253 Dacite Primary Ore Mineralization PD1-PR
4.4 0.72 0.06 0.21 0.43 2.73
298 to 342
Pixelate Ore Primary QZ-PR
5.1 0.53 0.02 0.10 0.38 2.75
Table 4, also explains the higher copper soluble in acid and soluble in cyanide and a
buoyancy without weak conditioning, behavior of new specific reactants. The pH value
even acid due do not have contained limestone rock in the mine which had been
maintained in the range of pH above 4.4-5.7 and close to 7.
Layers of oxides by weathering of the belts of porphyry are of different thicknesses, range from
300 m in the South to 25 m in the North and Centre, which possess a high solubility of copper
between acid, useful for processes of SX and EW in metallic copper. The transition layer with
very soluble secondary copper sulfides to assay in CN- , has a lower thickness reaching 10%
of the height of the total deposits useful for concentrated floating high laws between 28% and
48% Cu, finally being between 60% of height for the southern Strip and 85% of the belts
Center and North to the less soluble part of copper formed as primary sulfide flotation copper
concentrates enabling between 25% to 31% Cu.
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5.0 release of the particle size of ore to concentrate
The preliminary goal is the fineness of milling as stage of the concentrator plant that is
required to search for free those particles of sulphides of copper in the associations between
the metal values of copper, molybdenum, gold, silver and the gangue of iron, arsenic, clay,
etc.
In tables 5, 6 and 7 will wheelie in samples from the North Strip, the release of mineral species
for the range of 55% to 80% - 74 Micron size particles, Chalcopyrite, Bornite, Covellite and
Digenite species manage to RID only 73% of tennantite and to a lesser extent of pyrite and
gang silica. Persistent associations even in the fine fractions are between chalcopyrite and
tennantite. Molybdenite in an 87% releasing copper sulphide is accomplished but still persists
the association with clay, so it is expected to release additional stages fine until 80% - 10
microns for Regrinding of concentrated bulk.
Table 5. Release of copper ores in the ore food, northern area %
Fineness of grinding,
% - 0 074 mm
Chalcopyrite 、 Bornite 、 Covellite Digenite
Free particle Particle associated
With Tennantite With Pyrite With gangue
55 59.82 5.88 13.55 20.75
60 66.47 4.60 10.65 18.28
65 70.40 3.58 9.73 MBM 16.29
80 73.98 2.80 8.71 14.51
Table 6. Release of Tenantite in mineral feed, northern area %
Fineness of
grinding,
% - 0 074 mm
Tennantite
Particle released Particle associated
With chalcopyrite With pyrite With gangue
55 45.79 30.92 15.33 7.96
60 53.04 28.25 12.13 6.58
65 62.47 23.66 8.83 5.04
80 66.26 22.65 6.90 4.19
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Table 7. Release of Molybdenite in mineral feed, northern area %
Fineness of grinding,
% -0.074 mm
Molibdenite
Free particle Associate bargain
55 73.08 26.92
60 79.00 21.00
65 82.68 17.32
80 87.04 12.96
6.0 sampling of witnesses in North and metallurgical testing belt
Noting some samplings of deep diamond drilling in the North, in which with confirmatory
metallurgical witnesses for content of copper and arsenic in three levels: increasing As 150
ppm, 300 ppm As and 500 ppm As, corresponds less the copper content secondary sulphides
decreasing 50%, 47.2% and 43%; for depths of the layer of secondary sulphides between 20m
up to 200 m. depth, under only the primary copper in quartz up to 420m.
FIG. 5 CAMPAIGNS OF DRILLING INITIAL Y METALURGICO(AS 150-500 PPM)
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In the evaluation of metallurgical tests on the influence of the content of arsenic in this
porphyry copper to be floated, as shown in table 8; secondary copper sulfide concentrate is
enriched in greater proportion when less is the presence of arsenic, which leads to the
buoyancy of the tennantite against the bornite, chalcocite, and less easily adsorb xanthate
collectors and thionocarbamates in the group stage.
Table 8. Relationship enrichment of arsenic, copper, and molybdenum
Sample Head, assays Feed Separation Flotation, Assays Enrichment Ratio
CU, % As, ppm MO ppm CU, % As, ppm MO ppm CU As MO
Confirmation of the test of these concentrates by diffraction of X rays, table 10, shows us for
example that the complex compound Clinoclase as Cu hidroxo-arsenite, persists in copper-
arsenic concentrate. The porphyry copper in the Northern Strip in addition to this punish
arsenic, lead contents of Au and Ag which eventually help increase the value of payment of
concentrate.
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TABLE 10. X-RAY DIFFRACTION IN TEST METALLURGIC NORTH ZONE
CONCENTRATES
7. Chemical reagents of flotation copper - molybdenum - South Belt
Them stages of floating collective of floating bulk Cu-Mo, flotation of cleaning bulk Cu-Mo,
flotation selective of separation Cu and Mo, cleanings of the separation of Cu and Mo, in
addition to make is in agitated tanks of conditioning of liquids reagents, solid for pH, gaseous
of atmospheres oxidizing, inert, dispersing u oily collectors, surfactants, liquid dispersants,
flocculants, alcohol sparkling, non humidity, anti-fouling. Those who act on the chemistry of the
surfaces of the mineralized frothed- particles for their physical separation automated
mechanical strong agitation flotation cells, air insufflated to float bubbles and downloads
bargains not floated, as well as pneumatic cells and petroleum for thermal drying. Table Annex
A-2, summarizes the consumption of reagents in typical use in the southern belt
1 RESULTS OF TREATMENT BY PROFUNDIZACI AREA OR N OF THE PORPHYRITIC COPPER
8. Selective separation of concentrates
Copper concentrates with Arsenic in the mineralized belts of the Centre and North:
The routes of processes of treatment whereas e.g. the greater species mineralized are different, as is indicate some of them:
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• Oxides of copper and sulfur secondary Cu with high Arsenic, sericite and little carbonate for the crushing, followed by the agglomeration or n Leach a. n in dumps 60 tonnes / to n or.
• Arsenopyrite FeAsS via oxidative or n-lixiviation acid bacteria in 120 hours is solubilized and precipitated in 6 stages of neutralization to pH about 6 with Caliza-Cal.
• Tennantite by oxidation to pressure or autoclive after drying in the team Holoflite, extracted copper, S ° and scorodite
• Enargite by roasting in atmosphere or oxidizing Sphere (Platsol, Geocoat) sets the escorodita AsO As4Fe.2H2Or allowing you to extract the copper to 98%
8.1. options of separation of arsenic in molybdenum concentrate, Belt Center:
8.1.1 leaching with FeCl3 (15%), CaCl2 (30%) at 85 ° C:
For the leaching of zone, for example with 1.37 molybdenum concentrate % Cu and 0.64% As
average will be reloaded at 30% solids by oxidation temperature in the reactor closed for 3
hours,
Has been revised the "Brenda" process in studies that is carried out on concentrates of the
central area recently, in where the extraction of copper of 78% and also the arsenic as
maximum arrives to the 60% of extraction to the same time, leaving still punishable remanent
arsenic
8.1.2 Leaching with NaOH (10%), Na2S (10%), CaCO3 (5%) at 85 ° C:
The process of removal of arsenic with NaOH (Reynolds, Denver Co. 1981), applicable to the molybdenum concentrate, is however judged that residue leaching with FeCl3, is appropriate for your application by the reaction and requires 6 hours of agitation:
3NaOH + FeAsO4 - Na3AsO4 + Fe (OH)... 85 ° C
For the additional withdrawal on this route, as initial reports removal of 80% As and unreferenced Cu and Sb, and instead as a second part allows a total removal of both stages of 86% Cu and approximately 88% As
In such a way that molybdenum concentrate low As content to 0.11% and is thus suitable for their marketing.
Using an oxidant conditioning As2S3, seeks to reduce the buoyancy of the concentrate of high grade of arsenic and fraction with low content of Moly and instead concentrate the fraction of molybdenum concentrate with lower content of As2S3, until the commercial Molybdenum degree. The second fraction by weight,
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which is much smaller, with high content of As2S3, is leaching for example with H2SO4 + CaCl+O2 at 100 ° C for 7 hr.
Conditions mechanical leaching, filtering, drying, as basic stages that would be included in a change process, according to the option that must be confirmed at the level of laboratory and pilot, affine scaling at the industry level to define management and cost of approximately for example of 21 MTPD for Moly concentrate and by-products, that will also recover the residual heat of the drying process used for the stages of heating of pulps to 85 ° C.
FIG. 5TH KINETICS OF DISSOLUTION OF ARSENIC
8.1.4. Bulk de Chalcopyrite, Tennantite-Enargite and sphalerite flotation
It is known that copper concentrates containing As about 0.3% are not received by the
smelters, so copper with As gangue minerals must follow a mitigation Protocol. Copper
porphyry in this problem is still manageable, instead deposits with mostly of zone massive
sulphide Center of Peru, with chalcopyrite sulfides is the attached table 11 as example,
enargite in gangue pyrite and sphalerite should concentrate as bulk phase, then do a quick
Chalcopyrite with minimum floating As and then put up the flotation of Enargite-Tennantite for
hydrometallurgical treatment. Using the consecutive stages of selectivity.
Productos % Peso Cu Pb Zn Ag *Onz/t Fe As Au* Onz/t CuO Cu Pb Zn Ag Fe As Au CuO