The Jonnagiri project is one of the most well developed, construction-ready, gold projects in the country offering strong cash flows over next 8-10 years. Open-pit mining operation and simple Metallurgy the gold ore make this project highly profitable.
Gold mineralization in the ML area is distributed in 4 blocks, namely East, West, South and North Blocks. Geomysore has conducted detailed exploration in the East and West Blocks, to achieve 361,000 ounces of Mineral Resource (JORC Indicated and Inferred categories), out of which approximately 271,000 ounces is open pit.
Detailed drilling and rigorous internal evaluation of results indicate the presence of 6.8 tons of mineable gold in the open pit of the East Block for a total depth of 180 m, with a mine life of 8 to 9 years. Upon further detailed drilling in the remaining blocks, the resources could potentially increase to 14 tons of mineable gold, with a mine life to about 15 years.
In order to achieve the production of mentioned quantity of gold, a processing plant with a capacity of 1000 TPD is considered. The EC and CFE for a 1000 TPD is already approved.
The project is expected to start the full scale commercial production from the third quarter of 2024. Pilot scale production is already commenced.
Jonnagiri greenstone belt is part of Eastern Dharwar Craton and known for gold mineralization which has been exploited since ancient times. Old debris and pounding marks indicate that the area has been worked by the ancients for recovering gold. These ancient workings attracted the attention of the Geological Survey of India to carry out detailed investigation in 1991- 1994.
The exploration work by Geological Survey of India (GSI) led to the identification of five blocks viz.; Gavanikonda, Dona West, Dona East, North and South blocks of which the Dona West and East blocks were found to have significant potential for gold mineralization. The exploration by GSI involved 3297.65 m of diamond core drilling in West block and 5183.20 m of drilling in the East block. Based on drilling results GSI estimated a gross probable reserve of 0.446 million tonnes with an average grade of 4.27 g/t Au for Dona West block. Similarly, a probable reserve of 7.77 million tonnes at 1.79 g/t Au was estimated between 410 m to 230 m RL in East block.
In West block, gold mineralization was established within silicified metabasalt over a strike length of 700 m. In East block, which is located 1.2km East-South-East of West block the major rock type belongs to granodiorite-tonalite suite, which shows intrusive relationship with the schist belt. Above Map indicates the location of Jonnagiri Project in India.
Jonnagiri project has obtained all the government approvals, e.g., CFE, CFO, water withdrawal from a nearby canal. Currently land acquisition is in progress subsequent to which Geomysore is planning to erect and commission the processing plant and other infrastructure. Jonnagiri Gold Mine Project has been planned for a production capacity of 1000 TPD and enhancement up to 2000 TPD in terms of quantity as per approved Mining Plan and Environmental Clearance of the project.
Geomysore received the Environmental Clearance from Ministry of Environment and Forest valid till 20th October 2043
Government of Andhra Pradesh executed the Mining lease deed on 21st October 2013.
Geomysore has received for Consent to Establish (CTE) for 0.4 MTPA of Mining and 0.3 MTPA of Processing gold ore.
Geomysore has applied for Consent for Operations (CTO) for mining operations
Geomysore has valid a Mining plan from Indian Bureau of Mines till 31.03.2028.
Geomysore has received permission under Regulation 106(2)(b) of the Metalliferous Mines Regulations, 1961, to work with Heavy Earth Moving Machinery (HEMM).
Geomysore has received the approval to withdraw 0.021 TMC water from HNSS canal @138.5km for the Mining and Processing activities from Government of Andhra Pradesh
Geomysore has received the ROW permission for the construction of Water Pipeline from Panchayatraj department
Geomysore has received the ROW permission for the construction of Water Pipeline from Roads and Buildings department
EXPLORATION BY GEOMYSORE
Geomysore applied for a Mining Lease over an area of 5.97 sq km in the year 2006. The Government of Andhra Pradesh had advised Geomysore to submit an approved mining plan for considering the grant of Mining Lease. Accordingly, Geomysore submitted a Mining plan to Indian Bureau of Mines in 2008, which was approved on 04th August 2008. Geomysore also received the Environmental Clearance from Ministry of Environment and Forest in 2010 which is valid till 2043. Geomysore also received CFO and CFE for Jonnagiri Gold Project from APPCB.
Since the grant of Mining Lease, Geomysore has carried out extensive advanced exploration which includes trenching, soil sampling, IP survey, magnetic survey and drilling. About 33,000m of close spaced drilling has been done from which Geomysore could establish 5.7mt at 1.45g/t with a gold content of 8.28t in East block, 1.1mt at 2.98g/t with a gold content 3.28t in the west block and 0.05mt at 1.77g/t with a gold content 0.1t in south block. Geomysore has completed NI43-101 compliant Feasibility Study on Jonnagiri Gold Project, which is the first such study to be done on any gold project in India. As a part of this, Geomysore has carried out all the technical studies eg., drilling, resource estimation, ore beneficiation studies, Geotechnical studies, pit optimization and scheduling, tailing dam design and other infrastructure items.
Pit optimization in East Block shows that the ore can be economically mineable by open pit method up to the depth of 180m and the quantity of ore can be mined is about 4mt with a gold content of 6.5t at 0.6g/t cut-off.
RESOURCES & GEOLOGY
The Jonnagiri ML is located near the Jonnagiri, Erragudi and Pagadirayi villages within the Tuggali Mandalam in the Kurnool District of Andhra Pradesh. The Jonnagiri village lies on the Gooty–Pattikonda State Highway. The nearest town is Gooty, which is located on the Hyderabad– Bangalore National Highway No.7 and situated 250km north of Bangalore. The nearest railway station is at Pagadirayi which is the broad-gauge line of South-Central Railways. Gooty Railway Station is situated on the Chennai-Guntakal broad gauge line. Geomysore has a granted ML covering 597.82ha (1,477.24 acres), the center of which is situated at about 3.0km northeast of Jonnagiri Village. The Project is located in an area which is known for ancient gold and copper mining activity.
Jonnagiri ML is situated in the Late Archaean Jonnagiri greenstone belt (JGB) of Eastern Dharwar Craton (EDC). JGB is an arcuate shaped belt, trending E-W to N-S with steep dips to N and E. The belt is dominated by Mafic and Felsic volcanic rocks with subordinate amounts of sedimentary rocks. JGB has undergone greenschist facies metamorphism, Cheval with greenschist facies metamorphism and syn- to post-kinematic granitoid intrusion. Large scale obliqu-slip shear zones along the margins of the belt, particularly along Eastern and Southern margins. These shear zones aided the intrusion of granitoids and also provided pathways for auriferous solutions. Granitoids are dominated by granodiorite with subordinate amounts of diorite and granite. Jonnagiri ML is situated along the southern and Eastern margin of the belt, where both ENE-WSW and N-S shear zones in the granodiorite provided the pathways for auriferous fluid migration and precipitous. Gold mineralization is mainly located in the granodiorite with minor amounts hosted in quartz veins emplaced metavolcanic rocks.
Gold mineralization in the ML area is distributed in 4 blocks, namely East, West, South and North Blocks. Geomysore has conducted detailed exploration in the East and West Blocks, to prove 361,000 ounces of Mineral Resource (JORC Indicated and Inferred categories), out of which approximately 271,000 ounces is open pittable. The optimized open pit of the East Block, which was done in the year 2017, contains about 150,000 ounces to a depth of 120m of Probable Mineral Reserve and Geomysore has pursued the detailed Economic Feasibility on this resource. The mine life based on 2017 pit optimization is about 7 years. Recent internal estimates show that the East Block open pit can be expanded to a depth of 180m which would contain 200,000 Oz of resource and increases the mine life to 10 years. In addition to the East Block, resources have been identified in the West block and South block, which can be further developed through detailed drilling. These resources could potentially increase the resource to 0.5MoZ and the mine life to about 15 years. The disposition of mineralized blocks within the ML area are shown above.
Based on the exploration carried out in the Jonnagiri ML, Geomysore has estimated the resource for East and West blocks. The Mineral Resource estimation and classification of Mineral Resources for the Jonnagiri Project was completed by Mr. Andrew Weeks who is a Fellow of the Australasian Institute of Mining and Metallurgy.
Mr. Andrew Weeks has sufficient relevant experience to the style of mineralisation and type of deposit under consideration and to the activity for which he is undertaking to qualify as a Competent Person as defined in the JORC Code (2012 Edition).
A) EAST BLOCK
The East Block is situated the eastern part of the ML Block and extends over an area of 35ha. It is a N-S trending block, which is separated from the west Block by a NE-SW trending major dolerite dyke. Barring a few outcrops in the block, this is largely concealed under a thick cover of soil and ancient mine rejects. This material, which is generally called as “Debris” is an admixture of soil with angular blocks, boulders, cobbles and pebbles of waste rocks ( scree/colluvium) and mineralized rock (quartz vein) which were discarded by the ancient miners. It attains a maximum thickness of about 4m along the ancient pit in East block. The thickness reduces to around 3m elsewhere in the East Block.
Geology of the East block is constructed based on these few outcrops and drill hole data. The average surface elevation of the East Block is 428m and is spread over an ancient artisanal working, which trends N-S and extends over 500m along strike with an average width of 40m.
Observations made on the limited outcrops indicate that the East Block is composed predominantly of medium-grained Granodiorite, which at places exhibit intense brittle to brittle-ductile shearing. Trend of the shear zones vary from N-S to NNE-SSW with moderate to steep westerly dips. Where ever found this stretching lineation’s plunge towards NW.
Trenching carried out by Geomysore shows that the East Block has nearly 3-4m thick soil cover mixed with angular boulders of rocks. The angular boulders appear to have resulted either from natural breaking down of the bed rock or from the ancient mining activity. The relative proportion of the angular blocks and boulders in the top layer decreases away from the ancient mining areas. The following image represents view of the East Block.
B) WEST BLOCK
The West block trends NW-SE and covers an area of 32ha. West Block is located in the vicinity of the granite-supracrustal contact. Detailed mapping and observations from the drill cores indicate that the contact between supracrustal rocks and granite in curviplanar, with trend varying from WNW-ESE to NE-SW.
The supracrustal rocks in the West Block are represented by metabasalt and metarhyolite. The contact between these two trends WNW-ESE. the dominant structure is the foliation, which trends N80W-S80E and steeply to the NNE. Gold mineralisation in the West Block occurs along WNW-ESE trending lodes in the metabasalt and along NNE-SSW trending shear zones within the granodiorite. The following image indicates the view of the West Block.
C) NORTH BLOCK
North Block occurs to the north west of the East Block. Although there are only a few outcrops in the area between East Block and North Block, the avilable structural data suggest a possible North-westerly swing to the main shear zone from east block to North Block.
The North Block exposes coarse grained granodiorite with thin shear zones. Mylonitic foliation trends NW-SE and dip at moderate angles to south west. Although there are occasional sulphide disseminations on the outcrops, there are no old workings in North Block.
D) SOUTH BLOCK
South Block is the southern extension of the West Block into the dominantly granite. The granitic rocks here show the presence of a few NNE-SSW to ENE-WSW trending shear zones, which dip NW at moderate angles.
Four such shear zones have been mapped, which are separated by less deformed granitic rocks.
These brittle-ductile shear zones often show the presence of thin quartz veins and sulphide disseminations.
The Jonnagiri Gold Mine project was developed based on the pit optimization outputs considering East Pit as a standalone scenario targeting 495ktpa at a cut-off grade of 0.6g/t.
The current Mining Plan permits the mine to operate at 0.4 mtpa for mining. The current Mining Plan has to be renewed every 5 years. Mining in East block is planned with Open pit operation with drilling and blasting is planned.
The proposed pit would progress from Northern to South. The bench height is planned at 7.5 m and the operating/ working width of the benches will be 10 m and the final width will be 6 m due to its highly compact and hard nature.
Worked-out benches shall be planted at the end of life of mine.
The modelling process carried out by Ukwazi South Africa is based on model types with specific block dimensions: Resource SMU model block dimensions & Mining block model or smallest/selective mining units (SMU).
Two mine design SMU models were generated by Golders for Ukwazi to establish the most suitable SMU size for the level of selectivity required for the mining operations. The SMU sizes investigated were: 5m x 5m x 2.5m & 5m x 5m x 5.0m.
The image indicates the isometric view of the East Block Pit Design and Selected Pushbacks.
Based on the metallurgical evaluations that have been completed, the Jonnagiri ore is a free milling gold ore with a considerable gravity recoverable component. The metallurgical test work programme has been conducted primarily at the facilities of SGS Johannesburg, South Africa with additional evaluation being conducted at the Indian Bureau of Mines (“IBM”) facility in Bangalore.
Series of metallurgical evaluations, Heap leach potential, Comminution work, Gold deportment studies, Gravity evaluation, Gold extraction leaches, CIL Optimisation test work, Fineness of grind, Reagent consumption, Leach time evaluation, Slurry density evaluation, Oxygen requirement, Thickening and Settling evaluation, Viscosity evaluation, Detoxification requirement studies and Environmental evaluation were conducted on the drill samples or selections and composites of these samples.
GOLD RECOVERY ESTIMATE
The gold recovery estimate, as developed for the Jonnagiri Gold Project, has been based on test work completed on the medium-and coarse-grained samples. The results of which were modified by ‘White’s Rule’, which is an empirical relationship between head grade and tailings value, in an attempt to predict the grade-recovery relationship. The leach recovery curve as developed during the variability test work and smoothed is shown in the figure.
The mentioned test works served as the basis for selecting the process design. The comminution circuit will consist of a three-stage crushing plant followed by a ball mill in closed circuit with a hydro-cyclone to treat nominally 1,000 tonnes per day at a milling rate of 50 tph. Further the processing circuit will consist of gravity gold recovery, cyanide leach with Carbon in Leach (“CIL”), carbon elution, electro-winning and smelting of doré, tailings detoxification for contained cyanide followed by tailings disposal. The plant has been designed to comply with the process specifications as required by the project team for the 1,000tpd gold ore beneficiation plant.
PILOT PROCESSING PLANT
Until the commissioning of the final processing plant, a pilot scale processing plant consisting of recovery of gold using gravity technique has been already established with the design criteria as per the conducted test works. The processing capacity of this plant is 2 tons per hour.
This pilot plant has helped in understanding the commercial and technical aspects with enhanced assurance towards minimizing the risk on the final processing plant and on the entire project.
The pilot plant has the following technical specification
- Plant Capacity: 3 TPH
- Crushing : Two Stage
- Grinding : Ball Mill
- Gravity Separation : Knelson, Spiral, Shaking Table
- Smelter : 100 kW Smelter
- Plant Feed Grade : +1.5g/ton
- Gold Production : +1 kg/month
The image indicates the process involved in production of gold dore bar by smelting the gold ore concentrates.
To know more updates on Jonnagiri Gold Project please visit website: www.geomysore.com