b2b-team.eub2b-team.eu/_static/files/gce-geological-report.docx · Web viewThe pitting program established proven ore reserves totaling 316,326.5, and an average of 0.775m pay gravel

GOLD COAST EXPLORATION

KWABENG GOLD CONCESSION

GEOLOGICAL REPORT ON ALLUVIAL GOLD EXPLORATION

SEPTEMBER, 2015

Table of Contents

Introduction……………………………………………………………………………………1.0

Exploration…………………………………………………………………….……………….2.0

Assay.………………………………………………………………………………………….3.0

Calculation of proven ore reserves (Yardage)…………………………….…………………..4.0

Conclusion…………………………………………………………………………………….5.0

Mine Design…………………………………………………………………………………...6.0

Gold Coast Exploration Geological Report kwabeng September, 2015 Page 2

EXECUTIVE SUMMARY

Gold Coast Exploration, GCE, is to undertake mining activities on an alluvial gold concession at

Kwabeng in the Eastern region of Ghana. The concession is approximately 100 acres in size and

is largely underlain by the Birimian metasediments striking about 45 degrees south east.

To better understand the geology, mineralization potential and to establish target areas for

mining, an exploration program was initiated in September, 2015. The work involved active

stream sediment panning and test pitting across the 100 acre concession.

The goal was to delineate grounds within the concession that show economic potential for gold

mineralization. A total of 26,1m x 1m sized pits were dug from the top soil through the over

burden then to the pay gravel. The pay gravel was brought out and washed through a sluice box

and the gold concentrates quantified.

The pay gravel is mostly grey in color with more than 50% quartz pebbles, some sand and little

clay and silts. Generally, the pay gravel has a sandy matrix with very little clay can be described

as free wash type gravel meaning lots of pay gravel can be treated in an 8 hour working period.

Clayiness by visual inspection on the field showed variation in clay content in pay gravel from

5% to 19% especially at regions of quiet deposition like the river and stream beds.

The pitting program established proven ore reserves totaling 316,326.5, and an average of

0.775m pay gravel height. The proposed washing plant can treat 60 m cube per hour and

therefore 134400 m cube of pay gravel annually.

Generally, the gold within the concession occurs as fine grains. A larger portion of the 100 acre

concession showed high grade of alluvial gold deposition especially the river beds an areas very

close to the river, areas away from the river had average gold content and hilly areas within the

concession showed low gold composition.


The gold bearing gravels will be loaded directly into portable skid-mounted mobile processing

plant for treatment. The plant will be coupled to the excavator to position for in-pit processing.

In general, the exploration proved that, mining on the 100 acre concession is feasible and

economically viable since the area has a light vegetation cover, is close to a gold bearing stream,

and has a short over burden and lastly rich pay gravel.


1.0 Introduction

GCE is registered as a limited liability Company in Ghana to work an alluvial gold concession

location at Kwabeng in the Eastern Region of Ghana. The company has very cordial working

relationships with the Government of Ghana, regulatory agencies and more particularly, local

communities within and proximal to the concession area.

1.1.0 Geology

The principal rock units occurring in Ghana are the metamorphosed and folded Paleoproterozoic

rocks of Birimian, Tarwaian and associated mainly granitoid intrusive to the west and northern

parts of the country.

The Pan-African mobile belt terrane of eastern and southeastern Ghana consists of the

Dahomeyan Units (mafic and felsic gneisses, probably rejuvenated Archean and/or Proterozoic),

the Togo Units (quartzite, shale, minor serpentinite) and the Buem Units (shale, sandstone,

basaltic to trachytic lava and volcaniclastics)

One third of Ghana is covered by 3,000-4,000 m thick, late Precambrian to Paleozoic, flat-lying

shelf sediments of the Voltaian Formation (sandstone, shale).Locally restricted, shallow marine

basins of Devonian to Upper Cretaceous age- related to the opening of the Atlantic which occur

along the coast. Some of the latter sedimentary rocks are oil and gas bearing off-shore sediments.

Coastal sedimentary rocks, comparatively younger in age include the Sekondian and Accraian

formations (Junner, 1935; Kesse, 1885)

1.1.1 Local Geology

The concession is underlain by the lower Birimian supergroup, the Birimian supergroup in

Ghana features a series of narrow, sub-parallel generally northeast-trending greenstone belts of

mafic to intermediate volcanic, volcaniclastics and interbedded sediments intruded by

intermediate belt granitoids. ^The greenstone, six of which are conspicuously recognizable (i.e.

Kibi-Winneba, Axim –Ashanti, Sefwi, Bui, Bole – Navrongo and Lawra belts) are separated by

border metasedimentary basins which often show strong volcanic affiliation and are intruded by


massive granitoids. Pyroclastic deposits associated with the mafic lavas chemically similar to

tuffs may also be present in adjacent basins. The molassic but auriferous Tarwaian Group rocks,

preserved mainly in the Ashanti Belt are composed of clastic sediments mostly quartzite, arkose,

conglomerate and phyllite (Kesse, 1985).

A map showing the concession superimposed on Geo map of Ghana

1.1.2 Gold Mineralization within this Formation

Gold deposits are economically by far the most important mineral deposit type in Ghana.

Five important types of gold mineralization occur;

a) Steeply dipping quartz veins with native Au in shear zones at Birimian belt/basin boundaries

(e.g. Konongo, Ashanti and Prestea mines).


b) Disseminated sulfide bodies, spatially though not necessarily genetically in association with

the shear zones and quartz veins, with auriferous arsenopyrite as major host of gold (e.g.

Obenemase, Ashanti, Bogosu , Prestea mines).

c) Disseminated and stock work mineralization in late-kinematic “basin-type” granitoids (e.g.

Ayanfuri mine).

d) Modified paleoplacer mineralization in quartz pebble conglomerates of the Tarkwaian

Group, carrying detrital and reconstituted magnetite and hematite (e.g. Tarkwa, Teberebie,

Iduaprim mines).

e) Alluvial gold concentrations occurs within its basins and this is what GCE hopes to exploit.

1.2 Accessibility

In terms of accessibility, the major road connecting Accra to Kumasi is about a fifteen minute

drive away from the concession. There is also the availability of secondary roads that connect all

the towns located around the concession. A road has also been construction from the Kwabeng

second class road straight to the concession making movement quite easy.

1.3 Geographical Setting

The general topography of the region consists of low lying plains with prominent hills and ridges

ranging from 400 to 600m in the NE parts of the concession.

The concession area falls within the wet semi-equatorial climatic region of Ghana (Dickson and

Benneh, 1988). This region has two rainfall maxima, with a mean annual rainfall of about 200

cm. The first rainy season lasts from May to June, and the second one from September to

October. Relative humidity is normally around 75%. Mean minimum and maximum

temperatures are 180C and 300C respectively, while the average annual temperature is about

240C.


1.4 Infrastructure

The Kwabeng Police Station serves the inhabitants of Kwabeng, Muaso and their surrounding

villages and provides peace and security to them. Also located at about 2.5km east of Anyinam

on the main Accra-Kumasi Highway is another police station.

Almost all the communities around the concession area have access to basic education.

There are senior high schools (S.H.S.) within the concession area,

There is a health facility in Kwabeng serving other towns around the concession. There are

hospitals like Osino District Hospital, Anyinam Government Hospital, and Saint Jude’s hospital

at Nkwakwa which are better equipped.

Major towns within the concession area have access to common social amenities such as

electricity, pipe born water, post office and markets. There are also cells sites of the major

communication networks within the concession area and this makes communication a lot easier.

There are guest houses and houses from rent which can serve as accommodation for staff and

management.

1.5 Socio-Economic Activities and Community Relations

Prior to commencement of exploration, the company visited all interested persons within the

concession area and notified on the type of work to be done and assured them that no damage

will be made on any of their properties and even if made, they will be fully compensated.

Most inhabitants within the concessional area are into farming, hunting, timber cutting and petty

trade as a major source of livelihood. Cocoa, oil palm and citrus are the main cash crops, while

plantain, cocoyam, cassava, maize and vegetables are cultivated mainly for domestic

consumption.


2.0 Exploration Activities

A 1m x1m frame was used during pitting to ensure accuracy in sampling a meter cube volume

of the pay gravel. The pay gravel was sampled manually and washed for gold concentrates using

a sluice box.

A total of 20 pits were dug within the concession with the aid of shovels and pick axe. The pay

gravel was dug onto a rubber material spread over the ground to avoid contamination. These

were then carried to the washing site which was normally along the river banks for washing and

the concentrates to be trapped in blankets laced on the sluice board using the gravity method.

There were three digging and washing gangs using basically shovels, water pumps, and pick axe.

Some of the walls caved in thus having abandoned them at whatever depth it was.

All samples dug were logged into a pitting logging sheet for subsequent entering into the

database for analysis. The Microsoft Office Excel software was used in the data entering and the

more technical geological analysis of the data picked in the field was done with the MapInfo

Discover software.


A picture of a gang digging a pit

2.1 Pay Gravel Description

The pay gravel is mostly grey in color with more than 50% quartz pebbles, some sand and little

clay and silts. Generally, the greater the clay content the more difficult it is to wash. The

washability varies from free wash, normal wash to difficult washing. Pay gravel with a sandy

matrix with very little clay can be described as free wash type gravel. A sandy clay matrix has a

normal wash, while a plastic clay matrix and the terrace deposit were difficult washing. Gravel

washability determines the amount of pay gravel that can be treated in a day. Clayiness by visual

inspection on the field showed variation in clay content in pay gravel from 5% to 19% especially

at regions of quiet deposition like the river and stream beds.


Pay gravel

Mineralization on the concession is mainly placer gold deposits, the hills might also be

mineralized but is currently unexplored. Most of the geological work was placer gold bias

meaning priority was given to the valley floor exempting the hills.

A vertical profile from the trenching done showed three layers;

The first layer, layer A, is the overburden which is mostly clayey, brown in color, with an

average thickness of 2 meters and 1.1 meters at places relatively closer to streams. It contains

some amount of gold but based on the exploration works and the grade currently being mined

generally in Ghana, its gold content is not in commercial quantity.


The second layer, layer B, is currently the pay zone for the company, it is mostly made up of

quartz gravels with a little amount of sand in a clay matrix. It is grey in color being deposited in

the Precambrian hence not oxidized and has an average thickness of 0.8 meters.

Layer C is the bedrock; it is schist, dark brown to black in color. It underlies the gravel layer

dipping almost vertical.

A vertical profile of the pit

During the pitting, it was observed that areas within or close to hill zones had slim to no gravel

layer within them, so it can be concluded that there are no alluvial gravel deposits in the hills.


Layer A (Overburden)

Layer B (Pay gravel)

Layer C (Bedrock)

3.0 ASSAY

A meter cube of gravel was taken from each pit and washed with a sluice box.

Gravel being washed with a sluice box

The fine sand trapped on the sluice box was later panned down and the gold extracted from the

concentrate with mercury. The gold was weighed on a micro scale and the product of its weight

against the one meter cube gravel it was obtained from gave its grade.


Gold particles in one of the concentrates


Table 1: DATA OF TOTAL GRAVEL GRADE AND THICKNESS CALCULATION IN TEST PITS

Pit ID GOLD GRADE(g/m3)

GRAVEL THICKNESS(m)

GCETP001 0.9 0.6GCETP002 1.1 0.8GCETP003 0.7 0.8GCETP004 0.8 1.1GCETP005 0.48 1.0GCETP006 0.3 0.8GCETP007 0.59 0.7GCETP008 0.59 0.4GCETP009 0.34 0.5GCETP010 0.48 0.8GCETP011 0.81 0.8GCETP012 1.2 0.7GCETP013 1.6 0.8GCETP014 1.32 1.0GCETP015 1.52 0.9GCETP016 1.18 0.8GCETP017 1.31 0.6GCETP018 1.4 0.8GCETP019 0.22 0.8GCETP020 0.12 0.8

From the table it can be seen that out of the 20 pits dug, 11 had grades from 0.8 meter cube and

above, 5 pits dug had grades from 0.79 to 0.4 meter cube and 4 pits dug had grades from 0.35

and below.

The analysis of the assay result has shown that a major portion of the concession has high gold

content, with the hilly NNW corner showing low grade.


A thematic map showing gold distribution across the concession

LEGEND

Large Red Circles - Pits with grades of 0,8m cube and above

Medium Yellow Circles - Pits with grades ranging from 0.75 to 0.4

Small Green Circles - Pits with grades ranging from 0.39 and below

A larger portion of the 100 acre concession showed high grade of alluvial gold deposition as seen

in the map below, especially the river beds and banks, these are the portions on the map with red

zonations. Areas away from the river had average gold content; this was the south central portion


of the concession as indicated on the map with yellow zonation and hilly areas within the

concession showed low gold composition just like the NNW corner on the concession with green

zonation. This is laudable because alluvial gold is basically eroded by high energy stream from

lode gold in mineralized rocks, transported and deposited along river banks or beds were the

energy is relatively very low so most alluvial deposits are richer close to the river. As seen from

the map above, the concession has a good drainage system thus most portion are river banks or

beds and hence a major portion of it, showing high grade of alluvial gold.

A map showing the gold grade zonations on the concession

4.0 Calculation of Gravel Volume (Yardage)

The amount of gravel that will be available for mining throughout the mine’s life can be

determined as the product of the total valley floor and the average pay gravel thickness.


Total Yardage=Total Valley Floor x Average pay-gravel thickness

Total Valley Floor=100 acres

100 acres=0.408 km sq= 408,163.271m sq

Average pay-gravel thickness=sum of individual pay-gravel thickness of trenches / number of

trenches

Average pay-gravel thickness=Total pay gravel thickness / Total number of pits

= 15.5 / 20

= 0.775m

Total Yardage=Total volume of pay gravel=Total Valley Floor x Average pay-gravel thickness

Total Volume of pay-gravel =408,163.271 m sq x 0.775m

Total Volume of pay-gravel = 316,326.5 meter cube

So the proven ore reserve totals 316,326.5 meters cube.

4.1 Production Rate and Mine Life

The calculation of a Mine’s life is dependent on the Mine’s machinery and input, a Mine with

lots of machinery and high input will process its reserve faster and therefore have a much shorter

life than one with much fewer machinery. The Life of a Mine is the ratio of its reserve to the

amount of pay gravel it can process a day.

Total Gravel Volume=316,326.5 meters cube

The proposed treatment plant has a capacity of 60m3/h and it is planned to run for eight (8) hour

per day for 280 days per year. A total of 280 days with an average of 24 days per month makes

room for the taboo days.


Annual Treatment rate=60m3/h x 8 h/day x 280 days/year =134,400 meter cube

Consequently, the same amount of gravel has to be mined to satisfy the processing plant.

Mine Life (L) = Total Gravel Volume / Annual Mining rate

Mine Life (L) = 316,326.5 meter cube / 134,400 meter cube

Mine Life (L) = 2.3 years

5.0 CONCLUSION

The aim of every Mining company is to make maximum profit at a very low cost. The

concession has a light vegetation cover hence will have to pay little as compensations, also, the

overburden covering the pay gravel meaning the pay gravel will be reached at a relatively shorter

time and at a lesser cost. Lastly, the gravel has very low clay content making it a free wash and

hence lots of gravel can be washed in a day leading to high gold recovery.

It can be conclusively indicated that the proposed project is technically feasible, economically

sound and financially rewarding.

6.0 MINE DESIGN

6.1 Selection of Mining System


In selecting a mining technique for the project, the following were taken into account;

Technical and economic feasibility(of the mining method)

Maintenance of high standard of safety for both workers and inhabitants.

Minimal impact on the environment.

In view of the above, I propose that GCE mine the Kwabeng concession applying the technique

of strip mining.

6.1.1 Unit Operation of Strip Mining

The unit of operation of strip mining and the sequence in which they occur are;

Site Development

Preparing the surface

Removal of overburden

Excavation and piling of the pay gravel

In-pit processing of the pay gravel

Leveling of washed gravels and topping it up with the overburden for back filing.

6.1.2 Site Development

The mine site will be developed by constructing roads to create access in the mining blocks.It

also involves the construction of settling ponds and overflow canals.

6.1.3 Preparing the Surface


The operation will involve the removal of trees and other vegetation cover in preparation for

other mining operations. The light trees will be felled with the excavator and much larger trees

will fell with the chain saw machine. Quality timber species will be collected for civil works

within the mine while the remaining will be cut to pieces and dried as firewood for the

inhabitants.

The operation will also involve the removal and stock piling of topsoil to be used afterwards for

re-vegetation. Top soil is generally understood to be the soft layers of soil over which the current

vegetation has established its roots.

6.1.4 Removal of Overburden

Overburden is defined as the barren or non-ore material that overlies the ore and must be

removed to gain access to the ore. The overburden material will not be transported but side

casted for use during reclamation. A Cat 330 excavator will be suitable.

6.1.5 Excavation and Loading of Pay gravel

Once the overburden is removed, the gold bearing gravel is exposed and ready for excavation

and piling. In some places the ore is compact and a considerable amount of force will be required

for excavation.

At places very close to the stream, the exposure of the gravel is associated with the seepage of

underground and stream water unto the surface of the gravel. The water needs to be pumped out

first and the pay gravel carefully and tactically excavated.

6.1.6 In-pit processing of Pay gravel


The gold bearing gravels will be loaded directly into portable skid-mounted mobile processing

plant for treatment. The plant will be coupled to the excavator to position for in-pit processing.

6.1.7 Leveling of Washed Gravel (tailings) for Backfilling

The tailings, which will be made up of washed boulders, cobbles, pebbles and sand will be

periodically leveled in the mined out areas for backfilling. This operation will be carried out

simultaneously with the mining. This means that an additional excavator or a dozer will be

required to assist both in the overburden removal and also for the leveling.

REFERENCES

Asihene K.A. B. and Barning K. (1975) A contribution to the stratigraphy of the Birimian


System of Ghana, West Africa. Ghana Geological survey Report 75/5, Accra, 30p

Davis D. W., Hirdes W., Schaltegger U., Nunoo, E. A. (rgg4) U/Pb age constraints on

Deposition and provenance of Birimian and gold-bearing Tarkwaian sediments in Ghana,

West Africa. Precambrian Research 67, gg-107

Dickson, B. K. and Benneh, G. (2004) A new geography of Ghana. Longmans Group Ltd.,

London

Eisenlohr B. N. Hirdes, W. (1992) the structural development of the early Proterozoic Birimian

And Tarkwaian rocks of southwest Ghana, West Africa. Journal of African Earth Sciences 14,

313_325

Hirdes W. Davis D. W., Eisenlohr B. N. (1992) Reassessment of Proterozoic granitoid ages in

Ghana on the basis of u/Pb zircon and, monazite dating. Precambrian Research 56, g9-96

Junner N. R. (1935) Gold in the Gold coast. Gold coast Geological Survey Memoir, 4,52p

Kesse G.O. (1985) the rocks and mineral resources of Ghana.

Leube. A., Hirdes, W., Mauer, R., Kesse, G. O. (1990) the Early Proterozoic Birimian

Super group of Ghana and aspects of its associated gold mineralization. Precambrian

Research 46,139-16



Documents

b2b-team.eub2b-team.eu/_static/files/gce-geological-report.docx · Web viewThe pitting program established proven ore reserves totaling 316,326.5, and an average of 0.775m pay gravel