Reagent mixing & Thickener unit

INTRODUCTION

MIDROC GOLD MINE is located in southern Ethiopia some 500 km south of Addis Ababa. This plant is gold recovery plant established 20 years ago its former name was Adola gold mine enterprise & it is privatized by sheik- Mohammed Ali Alamode 11 years before .A lot of improvement has been made in different sections of the plant since then to increase the throughput of the plant.

Open pit

Open pit yearly rock (ore +waste) mineral push back

3.5 million Tones

Ore 1.2 million @2.44 g/t

Waste 2.2 million

Steeping ratio 1:9

Equipment

DRILLING 3 Pantera 1500

2 CM780 D

2 DM45 E

LOADING 5 Excavator

2 loader

HAULING 9 773D

2 775E

4 769C

4 769D

Legadembi Underground

Production : 217000 t/ year

Grade : 3.5 g/ton

Mining method : Cut and fill stopping

Access to the vain

through decline of 10%

size 6 meter by 6 meter

located approximately 3km from the plant

Sub-Level Interval: 20 meter floor to floor

Access to stopes: spirals with cross cut at mid point

The method adopted, with current geotechnical knowledge, is

a modified AVOCA.

Ventilation : through ventilation (ventilation decline)

Target ore body

Four mineralised quartz vein systems have been delineated.

Lens 1

Lens 8

Lens 9

Lens 2

Lens 1. Is the main target in in the mine.

MINING EQUIPMENT

based on the mining and development schedule and can be divided into four categories;

production,

development,

hauling and services

Production

3 x twin boom development jumbo used for footwall drives and cross cuts

2 x production jumbo:

4 x 4m3 LHD: used for mucking

Development

2 x twin boom development jumbo: used to develop the ramp, return air drives,

2 x 4m3 LHD: used for mucking ore and waste from all development headings

East Sakaro Mine Schematic

GEOLOGY AND MINERALIZATION

East Sakaro comprises a number of lithological units including

graphitic quartz mica schist,

amphibolite,

tremolite schist,

vein quartz,

metagranodiorite,

graphitic quartzite and pegmatite;

the graphitic quartz mica schist and amphibolite make up the bulk of rock types in the East Sakaro area.

The same amphibolite rocks lie above and below the quartz mica schist that hosts the mineralised quartz veins.

GEOLOGY AND MINERALIZATION

Two mineralised quartz vein systems have been delineated.

ES-Vein 1

ES-Vein 2.

ES-Vein 1 lies close to the quartz mica schist and amphibolite contact

a width varying from a few cms to 6m and a strike over almost 800m.

ES-Vein 2, within intensely sheared graphitic quartz-mica schist.

The vein ranges from a few cms to 25m in width and a strike length of at least 450m

The resource on which the mine development is based is the quartz vein within intensely sheared graphitic quartz-mica schist.

RESOURCES

The geological modeling indicates a resource for ES-Vein 2 of

506,000t at 20.40g/t Au, Based on a

1g/t Au cut off grThe

The mine design analysis has resulted in a mineable ore reserve of

543.5kt within ES-Vein 2,

based on a nominal 3g/t

ACCESS AND MINING METHOD

Access to the vain

through decline of 14%

size 5 meter by five meter

located approximately 1km from the plant

Sub-Level Interval: 15meter floor to floor

Access to the sub-levels of the stopes for the LHD is via cross-cuts, driven 4m by 4m.

The method adopted, with current geotechnical knowledge, is

a modified sub-level open stoping referred to as the modified SLOS method (AVOCA).

MINING EQUIPMENT

based on the mining and development schedule and can be divided into four categories;

production,

development,

hauling and services

Production

3 x twin boom development jumbo used for footwall drives and cross cuts

2 x production jumbo:

2 x 4m3 LHD: used for mucking

Development

2 x twin boom development jumbo: used to develop the ramp, return air drives,

3 x 4m3 LHD: used for mucking ore and waste from all development headings.

Crusher unit

MIDROC GOLD MINE has two crushing plants erected in parallel namely

Medina Crusher

Old Crusher

Jaw Crusher

Open circuit superior crusher

Throughput : 185-195 t/h

Maximum feed lump size : 650 -700mm

Superior Crusher

Capacity : 162 t/h

Discharge opening range : 44 -63mm

Hydro cone Crusher

Capacity :81 t/h

Discharge opening range :8 -25mm

Surge hopper

Vib. feedr

Hydro cone

loader

Vib.

feeder

Single togle

2 stock

Vib feeder

S-3000

superior

DD screen

hopper

Feeder 2

Hydro cone

Loader

Vib feeder

double togle

2 stock

feeder 2

superior

DD screen

Vib feeder

Final stock

RUN OF MINE STOCKPILE

MILL

Circuit type : Road mill open circuit

: Ball mill closed circuit

Throughput : 220t/h (dry)

Ore feed size : 13mm

The annual performance of the plant is as

Mill ore 1.2 million tones @ 4 g/t

Further size reduction takes place in the liquid media here. There are two types of mills namely Road &Balls, the crushed material from the crusher final stockpile initially conveyed to Road mill by means of vibrating feeder &conveyer belts fitted for this purpose .at the feed spot to the road mill, the ore will be mixed with water & lime solution.

Hydro cyclone

Discharge sump

Trash screen

Thickener

o/f pump

u/f pump

O/f tank

s/screen

Ball mill

Rod mill

Discharge pump

To leach tank

Reagent mixing & Thickener unit

Thickening : is a process accomplished in thickener tank (diameter 13m & height 7m). It is imperative to decrease the quantity of water . To maintain the pulp density between 50-52 %.

Reagent mixing: is the process of mixing lime, flocculent, and sodium cyanide to the solution.

Lime holding tank

Flocculent holding tank

Cyanide holding tank

Flocculent preparation tank

Lime mixing tank

Cyanide mixing tank

2x

war

Warm

pump

2x

mono

Warm

pump

Floccu

hopp

Mono

pump

Mono

pump

Lime

To leach tank

To leach tank

Process water

Process water

Cyanide

To thickener tank

Return line

Leaching : Thickener under flow is pumped to leach feed distribution box and then gravitated to the first of the six series connected leach tanks via sampler box where the feed is sampled by an auto sampler.

Leaching unit

Leach tank 1

Leach tank 2

Leach tank 3

Leach tank 5

Leach tank 4

Leach tank 6

To CIP tank

Thickener

Lime

Cyanide

Leach circuit

The purpose of regeneration is to reuse the eluted carbon being after organic mater removed by means of heat about 750c in absence of air in a rotary kiln feed continuously from carbon accumulated in the eluted carbon tank by means of dewatering screw feeder.

Carbone regeneration

23

1

2

3

4

6

5

Pump carbon

Furnace

screen

Activate carbon

Activate carbon

Jig

Horizontal screen

boiler

NaOH prepa tank

Vibrating screen

Acid tank

Water tank

Acid wash

To gold room

Recycle

Electrolytic tank

From horizontal screen

Heat

Tailing dam

1.The first dam: which is lied on wide area. All the slurry will settle in this dam while the cyanide containing water is floating at the top. Every day, sample will be taken from this dam before the cyanide containing water will be released to the second dam. It will not be released unless the cyanide concentration become about 20 ppm .

2.The second dam or reclaim dam: the purpose of this dam is to retain the cyanide carrying water and feed to the detoxification plant. Sampling is also carried out here.

The purpose this plant is to detoxify the cyanide containing water after nature degradation by adding calcium hypo-chlorite. This water will be released to the environment only being after sample test & confirmed that its cyanide content is less than 0.1 ppm. THANK U

Detoxification plant

CIP tail

First dam

Second dam

Detoxification plant

To environment

THANK U