.
- GEOLOGY
3.1. Location and Access Roads
Comisa and CBM are located in the municipalities of Itatiaiuçu and Mateus Leme, in the central region of the State of Minas Gerais, approximately 10 km South of the town of Igarapé.
The area comprises part of Serra das Farofas, an extension of Serra do
Curral (West side), within the Iron Ore Quadrangle.
Access to the area can be made, from Belo Horizonte, through Highway-381
– Fernão Dias, driving some 60 km up to the town of Igarapé. Driving 10 km
approximately in Highway 381 in the direction of São Paulo, Comisa/CBM´s areas
are reached.
There are two railroads in the neighborhood: CVRD´s system up to Port of
Tubarão (State of Espírito Santo) and MRS´s system up to Sepetiba (State of Rio
de Janeiro).
3.2. Regional Geology
The Iron Ore Quadrangle is located in the Southern end of the São
Francisco Craton (Almeida, 1977), a continental block composed of Archean and
neo-Proterozoic rocks.
The Iron Ore Quadrangle main geological units comprise the Archean
crystalline base and rocks belonging to the Rio das Velhas and Minas super
groups.
The Rio das Velhas super group - Archean age - is formed by rocks of
volcanic origin with the intercalation of sedimentary rocks. Among the
sedimentary rocks, iron ore formations of the Algoma type are separated and
commonly associated with gold mineralization.
Minas super group is discordant as compared to older units. Its age is
Paleo-proterozoic.
This meta sedimentary sequence comprises several lithologic types of
clastic nature - chemical of continental to maritime origin. (Figure 3.2).
Rocks of the Minas super group are outstanding features in the region,
producing the
highest elevations of the Iron Ore Quadrangle. Below are the Minas super
group units from basis to top:
Tamanduá and Caraça Group – Base
unit formed by clastic sediments, with sandstones and alluvial conglomerates
and maritime pelite rocks of shallow waters.
Itabira Group - An unit of
chemical origin, formed by banded iron features of the Lake Superior type.
Piracicaba Group -Thick unit
composed of marine sediments, with quartzites and phylites in frequent
intercalations.
Sabará Group - Turbidite and
volcanic unit discordant of the Piracicaba group.
Diamictites, conglomerates, pelite and tuff occur.
Besides the previous units the occurrence of the Itacolomi group is
observed near the thrust fault zones composed of coarse clastic sediments, with
sandstones and olymitic conglomerates. (Figure 3.3).
At least three orogenic cycles have affected the Iron Ore Quadrangle
rocks. The Jequié cycle aged 2,8 billion years is the oldest and is responsible
for the deformation of the Archean rocks. After the sedimentation of the Minas
super group rocks, the Transamazonic Event took place (some 2 billion years
ago), responsible for the intense deformation of all Iron Ore Quadrangle units.
The Brazilian Cycle, some 600 million years ago, has affected the Iron Ore Quadrangle
partially, in its East portion. (Figure. 3.4).
The Iron Ore Quadrangle complex geometry (Figure 3.5) is the result of
this tectonic evolution showing an architecture of domes and keels. The gneiss
complexes are situated in the domes and rocks of the Rio das Velhas and Minas
super group occurring in keels. The figure below (Ladeira & Viveiros 1984)
shows a regional geometric scheme, based upon evolution of folds.
The Iron Ore Quadrangle shows a metamorphic zoning from low temperatures
in the West reaching medium temperatures in the East, in the amphibollite
facies, according to indications by the metamorphic para-genesis.
The relief of the region has been formed since the end of the Mesozoic
era, with the generation of valleys, homoclines and plateaus, conditioned by
canga generation and formation of sedimentary deposits of predominantly lagunar
pelite and laterite, in restricted basis associated to extensive tectonic
movements (i.e. Florália, Fonseca and Gandarela).
3.3. Mine Geology
3.3.1. Preliminary Comments on DNPM Processes
Companhia de Mineração Serra Azul holds the following mining processes:
Number Year Name of Company
Phase of process Active UF
130 1959
COMP. MINERAÇÃO SERRA AZUL Expl. authorization Y MG
830145 1980
COMP. MINERAÇÃO SERRA AZUL Mine concession Y MG
830468 1980
COMP. MINERAÇÃO SERRA AZUL Mine concession Y MG
831304 1984
COMP. MINERAÇÃO SERRA AZUL Mine concession Y MG
831339 1984
COMP. MINERAÇÃO SERRA AZUL Mine application Y MG
831341 1984
COMP. MINERAÇÃO SERRA AZUL Mine application Y MG
831342 1984
COMP. MINERAÇÃO SERRA AZUL Mine application Y MG
830708 2003
COMP. MINERAÇÃO SERRA AZUL Exploration request Y MG
5736 1960
CBM-CONS. BRASILEIRO DE MINE Mine concession Y MG
Process 005.736/60 is not in the name of Comisa. However, it holds the
orresponding mineral rights.
All these processes are perfectly instructed (according to site
www.dnpm.gov.br) and are shown below, except for Process DNPM 830.708/03 which
is just a Request.
The drilling report, dated October 2003, prepared by Geoestrutural is
the major available and analyzed data among others in order to prepare a
preliminary appraisal of Comisa´s and Consórcio Brasileiro de Minerações´s
resources.
In this report processes DNPM 005.736/60, DNPM 831.341/84, DNPM
831.342/84, DNPM 830.468/80, DNPM 831.304/84, DNPM 830.145/80 e DNPM 000.130/59
were checked.
Therefore, processes 831.339/84 (a mine request) and 830.708/2003
(exploration request) were excluded from the calculations.
In order to compute the resources 5 (five) holes drilled during the
exploration phase were used as well as 14 (fourteen) new holes drilled during
2003, totaling 1.130 m, approximately.
For modeling purposes, besides these drill holes, geological mapping
(scale 1:3.000), interpretation of 14 vertical sections, with irregular spacing
and analyses of samples collected in the drill holes were utilized.
Geologically speaking, the area located in the Northwest border of the
Iron Ore Quadrangle shows a medium to high degree foliation (some 60°) and a
Southern dip, cut by high degree joints with NW-SE and N-S main direction.
The analyzed lithotypes were: Hematite, Siliceous Itabirites,
Siliceous/carbonaceous Itabirites, Cangas and Debris ore. The adopted
classification is as follows:
Compact Siliceous Itabirite– iron
grades below 40%;
Friable Siliceous Itabirite – iron grades between 40 and 63%;
Siliceous/carbonaceous Itabirite – iron grades over 45% and high alumina;
Friable and semi-compact Hematite – iron grades over 63%.
Density figures used in the calculation:
Siliceous Itabirite – 2,5 tonnes/m3;
Siliceous/carbonaceous Itabirite – 2,5 tonnes/m3;
Compact Itabirite – 2,7
tonnest/m3;
Hematite– 4,0 tonnes/m3;
Siliceous Itabirite – 2,5 tonnes/m3;
Siliceous/carbonaceous Itabirite – 2,5 tonnes/m3;
Talus – 2,5 tonnes/m3;
3.3.2. OPEN Mine Mapping of Comisa and CBM Mines
Comisa-CBM`s mining area strectches 3 km along Serra Azul (Blue Ridge).
Splitting mining rights areas into three portions (E and Central area and W
area) we find:
E area (East) shows a smaller representation in respect to mining
rights. However, near the product loading and stockpiling yard the largest
outcroppings of friable ore layer are found – very rich (around 62%) and a high
volume of lump ore, with a significant sinter feed fraction.
The central area of the mine indicates major iron ore exploitation, that
is to say, a larger pit development has occurred. The presence of approximately
three hematite lenses has been noted. In this central area several lithologies
are found, predominantly semi compact and compact itabirite.
e
Layers from North to South indicate an initial 40º dip. In the South
direction of the area a prominent dip is seen (around 60%).
Additionally, in the central portion towards the West, a large virgin
area is found and not mined yet, composed of large outcroppings of compact
itabirite.
Area W (West) is exploited nowadays to produce good quality and small
volume debris ore and canga. It is known as talus deposit area.
The appraisal phase comprised four days of quick mapping works,
inadequate for a better detailing of the ore body.
Access to the drill cores data was not possible, because there are no
drill cores in the mine site or even in Comisa´s office. The available
geological logs are not precise and drill holes are shallow. The iron ore
structure is itself a large folding, apparently cut in the Norte face. The closing
of the large fold corresponds to contact with the schist. In this portion of
the mine all schist structure for over 60 meters is sub vertical.
The compact itabirites are protore throughout Comisa´s mineral property.
Its alteration by hydro thermal process and secondly by weathering has
generated high grade ore bodies, presently mined by small Serra Azul miners for
over three decades.
The compact itabirites are intensely folded, at least, in two
directions. They converge towards the North direction. These efforts also
produced shearing zones more or less concordant with the axial plans, mainly in
the contact with base schists.
Compact itabirite form a large isolated mass in the mine center.
These are elevations similar to Itatiaiuçu Peak, in the nearby Global
Mine, limited by faults in the N-S direction, even in the East or West
direction. Outside this zone, the compact itabirite tends to form not
continuous concentrations.
These itabirites show a strong silica influence, reflecting very hard
and gray zones.
The semi compact itabirite form 30 m height benches. It is highly
difficult to estimate the gradation depth of this type of material for the
compact. However, according to information available, the transition from one
type to another is deeper in the neighboring mines.
The rich friable itabirite shows an average 30 m width and can locally
duplicate the bed reaching up to 100 m width. Similar to other mines in the
area there is a trend towards the closing of the friable and rich ore at depth.
In average, throughout the neighboring areas this depth reaches 45 m.
Considering Comisa ore bodies are found allowing a selective mining with
30 m of excavation works.
The existing rule in Serra Azul establishes that as the mines get
deeper, the percentages of types change.
That is to say, the compact percentage increases. This situation points
to modifications in blending as time passes by.
Comisa´s geological features, in general, are quite similar to the other
mines in Serra Azul.
That is, we have a large mass of compact and semi compact ores, cut by
friable rich itabirite channels (point 171 photo). What varies from one mine to
the other is the percentage of each type (compact-semi-icompact) and the
vertical gradient.
As production scale increases the selectiveness will be less, therefore
changing the ROM variation. The scale must be adapted in order this variation
be the minimum.
Itabirites often show dips of 70 and 90 degrees.
An approximate volume of 8 (eight) million tonnes is estimated in the
sinter feed stockpile.
3.3.3. Comparison of Comisa Model and OPEN`s Estimate.
Comisa has calculated resources based on 14 vertical sections, on 14
drill holes and also on the surface map prepared by Geoestrutural.
Figure 3.6 shows the geological map prepared by Geoestrutural whereby
the semi compact Itabirite lithology was grouped into the friable itabirite
lithology.
Figure
3.6 – Geoestructural geological map
Tonnage was obtained calculating the lithotype volumes using the vertical
sections method. This method generates solids considering the interpreted area
in the sections, extrapolating the area up to the half distance between two
sections or the maximum distance as area of influence.
The resources of friable material found were:
RESOURCES
Lithotype Mass (tonnes x million)
Friable Itabirite ¹ 39
Compact and semi compact Itabirite ² 201,9
TOTAL ² 240,9
¹ source CBM report
² source: TARGET GMMA report
Comisa has calculated a total resource of 240,9 million tonnes of friable,
semi compact and compact ore. Considering approximately 100,9 million tonnes of
compact material, the friable and semi compact itabirite resource could reach
some 140 million tonnes.
OPEN Brasil & Associates carried out surface mapping works
separating the semi compact itabirite from friable itabirite lithologies.
Figure 3.7 shows the geological map prepared by OPEN.
Figure
3.7 – OPEN´s geological map
For comparison purposes the lithologies areas mapped by Geoestrutural
and OPEN were calculated. The lithologies of friable and semi compact
itabirites mapped by OPEN were compared to the friable itabirite lithology
prepared by Geoestrutural.
COMPARISON
OPEN (m² x 1000) - Geoestrutural (m² x 1000)
Friable itabirite 899,1 - 908,7
Compact itabirite 147,4 -102.5
TOTAL 1046,5 - 1011,2
DIFFERENCE 4%
In this preliminary phase OPEN believes the amounts estimated by Comisa
are accurate
considering the available data.
3.4. Modeling and Mineralization Calculation
The mineralization model was developed by OPEN Brasil & Associates
technical team. Surface mapping information has been used, 14 holes drilled and
83 samples chemically assayed.
The ore lithologies identified during the mapping phase were: canga,
friable itabirite, semi-compact itabirite, argillaceous itabirite and internal
waste of Compact itabirite. The Compact itabirite itself was considered waste.
Eleven (11) vertical sections were prepared in the SE-NW direction in a
irregularly spaced grid fit to the best drill holes.
Total resources reached 168.8Mtonnes considering the ore lithologies. A
pit was developed based only on the geometrical parameters and considering all
the potential resource.
Total “Inferred Reserves” inside the pit reached 149.7Mtonnes.
3.4.1. Data Base
The data base was handed over by CBM-Comisa in a *txt log file. OPEN
transcribed the log in a *xls file with 4 tables: collar, surveys, litho and
assays. OPEN adapted the CLV (lithological code used by Comisa) with the code
used by OPEN technical team.
The transcribed samples were assayed for Fe, Al2O3, SiO2, P, Mn, TiO2,
PPC, Ca, Mg and FeO.
The data base was compiled in the Access® software according to the
following structure:
Collar table (Table 3.1) indicates:
• hole_id
(drill hole name);
• x (East
coordinate);
• y (North
coordinate);
• z
(quote);
• max_depth
(maximum depth of the drill hole).
Table 3.1 - Header table
Assays table (Table 3.2) indicates:
• hole_id (drill
hole name);
• de (beginning of
the interval sampled);
• ate (end of the
interval sampled);
• Sample (interval
sample name);
• CLV (sample
lithological code);
• Fe (iron percent
grade);
• Al2O3 (aluminium oxide
percent grade);
• SiO2 (silicious oxide
percent grade);
• P (phosphorus
percent grade);
• Mn (manganese
percent grade);
• TiO2 (titanium oxide
percent grade);
• PPC (loss on
ignition)
• Ca (calcium
oxide percent grade);
• Mg (magnesium
percent grade);
• FeO (iron oxide
percent grade);
• Geogrupo
(homogeneous field identifiable to do the estimation and the
compositing).
Table
3.2 - Assays table
Litho table (Table 3.3) indicates:
• hole_id (drill
hole name);
• from (beginning
of the lithologic interval);
• to (fend of the
lithologic interval);
• Length (sample
length);
• Litho
(lithology);
• Description
(lithological description).
Table
3.3 - Litho table.
Survey table (Table 3.4) indicates:
hole_id (drill hole name);
depth_from (beginning of the survey);
depth_to (end of the survey);
dip (drill hole dip);
azimuth (drill hole azimuth);
max_depth (maximum depth of the drill hole);
Table
3.4 - Surveys table
The styles table 3.5 shows parameters to visualize drill holes.
OPEN Brasil & Associates has also received CBM-Comisa´s
topographical files.
Drill holes coordinates were checked with the topographical basis and
considered valid to this level of uncertainty.
3.4.2. Geological Resources Model
For the purposes of geological 3D modeling the lithologies identified in
the field were
adapted to the codes used in the drill hole description by CBM-Comisa.
Five (5) ore lithologies and (three) 3 waste lithologies in the vertical
sections modeling
were grouped.
The ore lithologies are:
• Canga (CG);
• Debris (ROL);
• Argillaceous
itabirite (IAR);
• Friable
itabirite (IF);
• Semi-compact
itabirite (ISC);
The waste lithologies are:
• Compact
itabirite (IC);
• Batatal phyllite
(FL);
• Cercadinho
quartzite (QTC).
Eleven (11) vertical sections spaced irregularly using the half distance
method and drill
hole projections were done (Figure 3.8).
Figure 3.8 - Vertical sections spaced irregularly.
Friable itabirite, argillaceous itabirite and semi-compact itabirite
lithologies were modeled (50 m depth layers inserted with compact itabirite 50
m spaced). The layers were modeled with an average dip of 60º to the South.
Cangas were modeled in the surface following the terrain contour.
Batatal phyllite and Cercadinho quartzite waste lithologies were modeled
as thrust faults with high angle near the surface and low angle in the largest
depth as in the thrust fault models.
The base line considered in the geological model was 1000 m and the
lateral limits are the limits of the terrain used in the model (Figure 3.9).
Figure 3.9 - Typical section.
The friable, argillaceous and semi-compact itabirite layers were modeled
using the geological map and drill holes data. Compact itabirite was considered
for the rest of the material in the Cauê formation between the Batatal and
Cercadinho formations.
The poligons modeled in the sections were triangulated among sections to
create the solid 3D. (Figure 3.10).
Figure 3.10 – Solids 3D Model.
3.4.3. Compositing
The samples were composited (8 m) respecting the lithologic interval and
corresponded to the modal of the sample statistical distribution.
The composites were collected at regular intervals with a minimum of
50%.
Files of composites were created for (4) four geological homogeneous
files: geogroup 1, composed of friable itabirite and argillaceous itabirite;
geogroup 2 composed of semi compact itabirite; geogroup 3 composed of compact
itabirite and geogroup 4 composed of debris and canga.
The lithologies that have the same behavior, similar density, grade,
physical and chemical features were grouped in the same geological homogeneous
field.
Table 3.6 below shows the composite summary of the drill holes by
lithologies.
Table 3.6 -
Composite summary
geogroup_1 56 47 9
geogroup_2 35 28 7
geogroup_3 10 9 1
geogroup_4 24 16 8
3.4.4. Statistics
The first step during statistical analyses consists in the tabulation
and representation of the
data set obtained in the sampling for each value categories.
Table 3.7 shows a statistical data summary analyzed for geogroup 1,
geogroup 2,
geogroup 3 and geogroup 4.
Table 3.7 - Statistical data summary.
Composite Grade Number of samples Minimum value
Maximum value Mean Variance Standard Deviation Coefficient of variation
Fe 47 17.246 63.811 46.536
98.008 9.9 0.213
SiO2 47 5.846 66.083 28.567
192.815 13.886 0.486
Al2O3 47 0.221 5.63 1.311
1.493 1.222 0.932
Mn 47 0.008 1.026 0.234
0.07 0.07 1.13
P 47 0.019 0.193 0.058
0.001 0.034 0.591
PPC 47 0.481 9.453 3.328
4.738 2.177 0.654
Fe 28 32.535 44.736 38.698
11.711 3.422 0.088
SiO2 28 34.384 49.519
41.505 16.323 4.04 0.097
Al2O3 28 0.054 2.104 0.865
0.349 0.591 0.683
Mn 28 0.002 1.276 0.161
0.075 0.274 1.695
P 28 0.014 0.083 0.036
0.000 0.020 0.567
PPC 28 0.37 3.804 1.577
1.539 1.241 0.787
Fe 9 29.334 45.782 35.000
25.538 5.053 0.144
SiO2 9 30.73 41.820 37.893
9.472 3.078 0.081
Al2O3 9 0.08 0.473 0.191
0.013 0.115 0.598
Mn 9 0.083 0.210 0.147
0.002 0.043 0.293
P 9 0.025 0.045 0.031 0.000
0.006 0.184
PPC 9 3.243 9.735 6.306
5.863 2.421 0.384
Fe 16 32.025 61.222 53.19
57.011 7.551 0.142
SiO2 16 3.449 48.689 18.562
148.542 12.188 0.657
Al2O3 16 0.513 6.479 2.208
2.702 1.644 0.744
Mn 16 0.033 0.449 0.062 0.015 0.122 1.973
P 16 0.024 0.292 0.096 0.006 0.078 0.806
PPC 16 0.903 8.276 3.149 5.456 2.336 0.742
Figures 3.11 to 3.16 show the histogram and the statistical data of the
composites used in the grade estimation.
Because of the small number of samples the histograms were designed for
geogroup 1 only.
Histograms are used to study the shape and the distribution of the
grades, the behavior of the mineralization and to help in the definition of the
homogeneous fields that will be estimated.
3.4.5. Geostatistics
Owing to lack of samples it was not possible to structure and prepare a
variogram model for the area.
3.4.6. Block Model
To carry out the geological modeling, mineralization potential modeling
and to calculate the mining material some assumptions were established.
The blocks were assigned with the solids triangulated from the vertical
sections. Because of the irregular drilling grid space about of 300 m (150 m to
480 m) some blocks below the surface topography were not assigned.
The blocks without lithologies were assigned as semi compact itabirite,
Batatal phyllite and Cercadinho quartzite. The contacts defined by the
geological mapping were utilized to define priority lithology in the block
model.
The density model used was the same used in Minerminas Project that was
defined by Prominas, a company with experience in this kind of work.
The IAR, ISC and IC lithologies were considered with the same density of
the itabirite calculated by Prominas.
To the other lithologies densities (Table 3.8) values adopted based on
known Iron Ore Quadrangle data.
Table 3.8 -
Densities model
Litho Density g/cm²
CG 2.93
ROL 2.93
IAR 2.63
IF 2.63
ISC 2.63
IC 2.63
FL 1.80
QTC 2.10
The software used to estimate the potential mineralization and the
minable ore in the area was the GSLib. The block model was not rotated. Table
3.9 indicates the origin and respective model sizes of the blocks.
Table 3.9 - Origin and respective model sizes of the blocks.
Minimum Coordinates 7774250 568800 1000
Maximum Coordinates 7776200 572000 1500
User Block Size 50 50 10
Min. Block Size 50 50 10
Rotation 0 0 0
The total difference between the 97% volumes was adequate for the
identification of the
solids in an irregular grid and in a limited drill holes area (Table
3.10).
Table 3.10 - Block model validation.
IC
212 600 000 219 623 420 103%
CG
75 000 15 759 21%
ROL
4 850 000 5 038 153 104%
IF
1 525 000 1 676 141 110%
IAR
8 225 000 10 614 577 129%
ISC
48 925 000 30 424 851 62%
Total 276 200 000 267
392 901 97%
The large difference between the semi compact itabirite occurs because
the blocks without lithologies were considered semi compact itabirite inside
the Banded Iron Formation. The difference between canga occurs owing to the
block size.
The attributes used to calculate of the estimated potential
mineralization are shown in Table 3.11:
Table 3.11 - Attributes used to calculate the estimated potential
mineralization.
dens Float - -9 lithological density
geogrupo Integer - 0 geogroup
lito Real - -9 lithology
teor_al2o3 Float - -9 al2o3 grade
teor_fe Float - -9 fe grade
teor_mn Float - -9 mn grade
teor_p Float - -9 p grade
teor_ppc Float - -9 ppc grade
teor_sio2 Float - -9 sio2 grade
Grades of Fe, SiO2, Al2O3, Mn, P and PPC were calculated to IAR, ITH, IF
and IC lithologies by the Nearest Neighbour method (NN).
For estimation purposes a maximum ratio of 10,000 m in XY and a maximum
ratio of 1,000 m in Z were used.
3.5. Resources and Reserves
According to JORC resources may be classified as Measured, Indicated and
Inferred following the criteria below:
• Measured:
Estimated resources with high level of confidence (tonnes, density, shape,
physical characters, grade and mineral content). Based upon detailed exploration.
• Indicated:
Resources estimated with reasonable level of confidence (tonnes, density,
shape, physical characters, grade and mineral content), without adequate grid
of exploration, with inadequate spacing to confirm the ontinuity of the ore bodies
and their grades. However, the spacing grid is sufficient to admit the continuity.
• Inferred:
Resources estimated with low level of confidence, inferred based upon geological
evidence. The ore body and grade continuity are assumed but not verified. Based
on outcroppings, gallery and limited drill holes or low confidence.
The calculated resources in the CBM-Comisa area were identified as
potential, in other words, they are not yet a resource but there is a
possibility to become so. The total volumes of the mineralization model are
represented in the Table 3.12.
Table 3.12 - Resources
Lithology
Thousand
Vol m3
Thousand
Tonnes
(wet)
Fe SiO2 Al2O3 Mn P PPC Litho n
Ore (*) 63 600 168.753 42,02 36,24 0,68 0,17 0,05 2,18 -
Total 276.200 727.891 37,61 38,06 0,30 0,15 0,04 4,32 -
4,96 IC
4,28 IAR
Internal waste 6.125 15.432 36,28 38,61 0,19 0,14
0,032
1,58 IF
Argillaceous
itabirite 7.403 19.469 49,78 23,38 1,03 0,31 0,059
1,25 ISC
Friable
itabirite 1.373 3.616 46,59 30,45 1,11 0,17 0,043
1,81 CG
Semi-compact
itabirite 44.033 115.806 39,23 41,54 0,58 0,15 0,036
4,03 ROL
Canga 75 220 60,85 8,86 2,84 0,01 0,026
4,96 IC
Debris ore 4.850 14.210 58,96 9,99 1,39 0,14 0,116
Compact 38,61 0,19 0,14 0,032
itabirite 212.600 559.138 36,28
(*) Ore = all lithologies - Compact itabirite
Because of spacing of the drill hole grid in
CBM-Comisa area and the lack of information, it was not possible to guarantee
the continuity of the geological layers.
The lack of drilling works also reflected in the
impossibility of doing a variogram model and as a consequence the grades do not indicate the best estimate.
The grades did not present trustworthy values, however they are the best
possible estimate of the average grades of the lithologies and the deposit.
3.5.1. Pit Design
To define the minable material “Inferred Reserve” within the project
area a pit has been projected without considering the geotechnical restrictions
and economics parameters.
Basically a pit was projected including all ore lithologies and the
minimum waste material.
The study was carried out for all potential material as an indication
study, considering the work as a Scope Study. Table 3.13 shows the “Inferred
Reserve” - minable material in the project area:
Table 3.13 -
Reserves
Lithology
Thousand
Vol m3
Thousand
Tonnes
(wet)
Fe
SiO2 Al2O3 Mn P PPC Litho n
Debris ore 4.775 13.991 59,03 9,92 1,36 0,15 0,115
4,05 ROL
Canga 75 220 60,85 8,86 2,84 0,01 0,026 1,81 CG
Semi-compact
itabirite 37.755 99.295 38,97 41,92 0,58 0,15 0,037
1,28 ISC
Friable
itabirite 1.193 3.137 48,83 27,7 0,75 0,19 0,042 1,57
IF
Argillaceous
itabirite 7.403 19.469 49,78 23,39 1,03 0,31 0,059
4,28 IAR
Internal waste 5.150 13.545 35,54 38 0,18 0,14 0,028
6,19 IC
Ore (*) 56.351 149.657 42,18 35,82 0,68 0,17 0,05 2,38 ORE
Compact
itabirite 6.400 16.832 35,54 38 0,18 0,14 0,028 6,19
IC
Phyllite 2.675 4.815 - - - - - -
Quartzite 400 840 - - - - - -
Waste 9.475 22.487 - - - - - -
Total
65.826 172.144 - - - - - - -
REM
0,15
MORE DETAILS AND VALUES ONLY WITH PRESENTATION OF "LOI".
CONTACT: caa_bc@yahoo.com.br or alonso1304@gmail.com
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