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Summary Under the Amu Darya alluvials at Samti is the world's largest unmined documented alluvial gold resource. It contains a resource of 23 tonnes of gold according to Russian drilling, and between 57 to 100 tonnes according to revision of Russian data by the World Bank Sustainable Development of Natural Resources Project (SDNRP).
The Russian reports show Samti is amenable to industrial-scale efficient gold dredging without use of chemicals or explosives, and without much dozing or trucking of materials.
It is considered possible to commence industrial gold dredging at 300 kilos a year, as early as summer 2015 and ramping up to a tonne a year in 2016 (45-50 million USD a year).
Introduction Huge alluvial (placer) gold deposits were once widespread in the world, but depleted first by artisanal miners and then by large gold dredges. Large gold dredges remain important in Siberia, Mongolia and China. The era of large gold dredges is virtually over in the West, with only one apiece active in California, Alaska and New Zealand. Meanwhile, for historical reasons, the world's largest drilled unmined alluvial gold deposit is under the floodplain of the Amu Darya river in north Afghanistan, at Samti.
Gold resources under Amu Darya floodplain The archives of the Afghanistan Geological Survey (AGS) contain substantial records of Russian drilling under the floodplain of the Amu Darya at Samti. The Russians explored with a set of several Soviet UKC-22M churn drills and proved 20.78 tonnes of gold (pure) considered as "economic reserves" and a further 2.1 tonnes sub-economic. With the much higher gold prices today, the sub-economic can be confidently reclassified as economic, giving a grand total of 22.98 tonnes of "economic reserves" under the soviet resource classification system, worth in excess of 1 billion USD in the ground @ 50 USD/gram.
The importance of the Samti alluvial gold resource was noted by the British Geological Survey (BGS), and the United States Geological Survey (USGS) but no detailed reassessment was attempted.
Revised estimate of gold resources The first indication of a significant upward revision of the size of the Samti gold resource was suggested by the GTZ Consortium (GTZ and Projekt-Consult) in the Capacity Building of the Afghanistan Geological Survey (CBAGS) component of the World Bank SDNRP project. This led to more detailed upward revision by Robin Grayson (2012) again as part of the World Bank SDNRP project.
The revised estimates are in the region of 57 (low estimate) to 79 (upper estimate) tonnes of gold pure, worth 2.8 to 3.9 billion USD in the ground @ 50 USD /gram.
Grayson (op.cit.) presents a reasonable expectation that additional areas of sub-economic resources might contain a further 10 to 20 tonnes of gold, bringing the total to 100 tonnes of gold, worth up to 5 billion USD @ 50 USD/gram.
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Points for discussion 1. MoMP could consider raising awareness of Samti worldwide immediately as part of a
'Gold of Afghanistan' investment promotion initiative linked to hard-rock gold tenders and contracts by MoMP, artisanal gold initiatives of MoMP; and archeological and historical gold treasures and coins of Afghanistan. AGS, CBAGS and MIDAS could put together a promotional package for this if requested to do so by MoMP.
2. A 6-strong team of male and female AGS staff is recommended to specialise in placer gold exploration and drilling, and a 14-day training visit made to Mongolia, including visits to a wide range of industrial placer ("alluvial) gold mines in the Zaamar Goldfield and inspection of all stages of the operations (mapping, drilling, resource calculation, dredging, wash-plants, concentrating, panning, gold refining etc).
3. 3 of the 6-strong AGS placer gold team would stay in Mongolia for 3 months as trainees of placer gold drilling companies near the large gold dredges and learn how to be placer gold drillers and how to calculate the gold grade present (mg/m3).
4. A Mongolian driller familiar with the Russian placer drilling rigs would supervise the AGS Khair Khana staff in refurbishing up to 3 of the 20 Soviet UKC-22M placer churn drills. The drills need extensive repair and spares, and it would also be necessary to purchase an additional new or reconditioned UKC-22M rigs from Mongolia or Russia. (Note: these rigs are significantly superior to equivalent USA placer rigs).
5. Special attention should be given to the solitary Soviet USBR-25M Bucket Drill stored unused at AGS Khair Khana depot. This is the ONLY type of drilling rig capable of accurately testing the gold grades of the Amu Darya alluvial gold deposits. It is recommended to use this rig for training purposes only, and to buy 2 new USBR rigs from Russia, in order to drill at Samti to recallibrate the older drilling by determining the appropriate correction factor.
Conclusions The Amu Darya floodplain alluvials at Samti contain 20 tonnes of placer gold according to Russian drilling with the "wrong" drill (UKC-22M). Re-drilling with the "right" drill (USBR-25M) is expected to increase the estimated resource by several orders of magnitude. The lower estimate is 57 tonnes, while the upper estimate is 79-100 tonnes. This substantial gold resource is mineable by gold dredges without requiring chemicals, explosives, trucks, dozers or draglines.
A crash-program should be able to put 3 AGS placer drilling teams in the field at Samti by early 2014 plus 2 placer bucket drills in mid 2015.
Some of the specialised placer drilling equipment is in AGS Khair Khana depot but in poor condition, but spares and entire rigs can be bought in Mongolia and Siberia.
Production may be possible as early as mid-2015 at an initial rate of 300 kilos per year (income of 15 million USD per year), subject to a) early refurbishment of the AGS placer rigs, b) purchase or new placer rigs, c) technical assistance from MIDAS and/or CBAGS, and d) intensive hands-on training in placer gold drilling for AGS staff in Mongolia during summer 2013.
The World Bank SDNRP assessment by Grayson 2012 is attached.
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Afghanistan Ministry of Mines February 5, 2012
Samti Placer Gold Deposit Robin Grayson MSc, MoM Environmental Adviser
SUMMARY
The author presents evidence that the Samti gold resource is 36 to 59 tonnes greater than proved by Soviet Churn Drills, constituting an additional income from gold sales of between 1.8 and 2.9 billion USD. The Soviet Churn Drills (= Cable-Tool Drills) used at Samti, although excellent and superior to USA Churn Drills, are industry-standard only for damp or dry placer sediments. In wet placer sediments Churn Drills recover only a fraction of the placer gold. The Soviets imported a Bucket Drill capable of determining the ‘correction factor’. The author found this Bucket Drill in the AGS Warehouse and it was never used. As ‘second best’, the author inputted ‘correction factors’ derived from re-drilling by Bucket Drills in the Zaamar Goldfield of Mongolia. On this basis, Samti is considered to be the world’s largest un-mined alluvial placer gold deposit.
Introduction
The Samti gold deposit is being promoted by the Afghan Ministry of Mines for commercial exploitation. The Samti project has received technical assistance from the Sustainable Development of Natural Resources Project (SDNRP). The Samti gold deposit is an alluvial placer under the floodplain on the Afghan side of the Amu Darya. As this river is an international border it triggers for SDNRP a special WB Safeguard Policy, OP/BP 7.50 for ‘Projects on International Rivers’.
The Samti gold resource was proved by Soviet geological teams and was well-known to the Afghanistan Geological Survey (AGS) and its importance was highlighted in regional studies by the British Geological Survey (BGS). Curiously Samti was seriously understated in regional studies by the United States Geological Survey (USGS). It was left to the GIZ Consortium (GIZ International and Projekt-Consult gmbH) to correct this oversight and rekindle interest.
The author presents new evidence in this report that the gold resource at Samti is 36 to 59 tonnes greater than proved by Soviet churn drills, constituting an additional income from gold sales of between 1.8 and 2.9 billion USD.
The evidence consists of realization that the Churn Drills (= Cable-Tool Drills) used at Samti, although being excellent and superior to USA Churn Drills, are industry-standard for proving gold in damp or dry placer sediments. In wet placer sediments Churn Drills only recover a fraction of the placer gold. The Soviets were evidently aware of this as they had imported a Bucket Drill capable of determining the ‘correction factor’. The author has found the Bucket Drill in the AGS Warehouse and inspection proves it has never used. As second-best, the author has inputted ‘correction factors’ derived from re-drilling hundreds of Churn Drill holes by Bucket Drills in the Zaamar Goldfield of Mongolia. On this basis, it is evident that Samti is the world’s largest un-mined alluvial placer gold deposit.
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Soviet placer drilling in Afghanistan
The Samti placer gold deposits were proved by Russian geologists using Soviet placer drills (model UKC-22M churn drills = cable tool drills). These Soviet churn drills are famous for their reliability in proving gold grades in placer deposits, and are indeed superior to American churn drills.
Figure 1: UKC-22M Churn Drills in action somewhere in north Afghanistan.
About 20 Soviet UKC-22M churn drills are stored in the AGS Khair Khana depot. Although many are beyond repair, at least 6 churn drills can probably be refurbished using spare parts that are readily available in Russia, where they are still manufactured and are still widely used in Siberia and Mongolia.
Figure 2: UKC-22M Churn Drills stored at AGS Khair Khana in Kabul.
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UBSR-25M Bucket Drill for WET ground
Russian placer geologists were aware of the underestimation of the gold grades by the Soviet UKC-22M churn drill in wet ground, for they evidently planned to use at Samti a special drilling machine – the UBSR-25M bucket drill – specifically designed for drilling for placer gold in WET ground. However, the UBSR-25M bucket drill was delivered to Afghanistan but never actually used, and instead was left behind by the Russians and stored at the AGS Khair Khana depot, where it remains today. It might be possible to refurbish it but this is not clear, and purchase of a new Russian Bucket drill is recommended.
Figure 3: USBR-25M Bucket drill stored unused at the AGS Khair Khana depot.
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Figure 4: Technical sketch of USBR-25M Bucket dril.
Figure 5: USBR-25M Bucket drill in action in the Zaamar Goldfield of Mongolia.
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Figure 6: USBR-25M Bucket drill in action in the Zaamar Goldfield of Mongolia.
Figure 7: Sketch of a USBR-25M Bucket drill mounted on a standard truck.
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Proof of gold losses by UKC-22M Churn Drill in wet ground
Repeat drilling of Toson Alluvial in Zaamar Goldfield, Mongolia
The author has assessed what he believes to be the world’s largest and best documented repeat drilling, on the Toson Alluvial in the Zaamar Goldfield of Mongolia, involving 382 churn holes and 542 bucket holes:
1984/85 - drilling began on the Toson Alluvial when soviet geologists drilled 32 prospect holes using standard Soviet UKC-22M Churn Drills with 245mm casing. This proved an average vertical resource of gold of 717mg/m2.
1986/87 - soviet geologists repeated the 32 holes by drilling alongside them new holes using a standard Soviet UBSR-25 Bucket Drill with 660mm diameter casing. This proved an average vertical resource of 2,087mg/m2 - more than 3 times as much gold! The churn drills lost >65% of the gold - nearly 72% if borehole #656/24 is excluded.
1988/89 - soviet geologists drilled a further 542 holes on the Toson Alluvial with the same Bucket Drills, consistently proving much higher grades and larger vertical gold resource than indicated earlier by the Churn Drills.
1997 - Golden Tiger Corporation, as vanguard of Toronto-listed Java Gold (JVAG on CDN) executed a large program of infill drilling, using the discredited churn drills, drilling another 352 boreholes spaced 80m apart along 16 lines across the width of the floodplain. According to a Java Gold press release: "Two hammer-and-bailer style drilling rigs [= churn drills] with 245 mm casing were used in this program." The 352 churn holes proved far lower gold grades than the 542 bucket holes, with the churn lines (low gold) alternated down the valley with bucket lines (high gold), 16 times in succession. The drillers said a correction factor ("enrichment factor") has to be factored in to bring the churn hole results into line with the bucket hole results. But the independent exploration consultants understandably demurred from agreeing such large correction factors. Java Gold had to ignore the grades of the 352 churn holes and instead confined itself to a desk study to recalculate the gold resources from the results of the 542 bucket holes.
Repeat drilling of Bayangol Alluvial in Zaamar Goldfield of Mongolia
1984/85 - drilling on the Bayangol Alluvial began when soviet geologists drilled 46 prospect holes using standard Soviet UKB-8 Churn Drills with 245mm casing. This proved an average vertical resource of gold of 1.449mg/m2.
1986/87 - soviet geologists repeated the 46 holes by drilling alongside with a 660mm diameter UBSR 25M Bucket Drill, proving an average vertical resource of 3.168mg/m2.
More drilling confirmed similar discrepancies existed on a 50km stretch of the Tuul, justifying the investment in a fleet of 5 large Siberian-built bucket-line dredges.
Without checking and discrediting of the churn drilling, it is unlikely that the 5 large dredges would have launched, halving Mongolia’s gold production in its painful cash-starved transition from a command economy to a market economy.
Repeat drilling of Big Bend Alluvial in Zaamar Goldfield, Mongolia
Repeat drilling at Big Bend analysed by the author, increased the gold resource sufficient for
major investment in a pair of cutter suction dredges which are to commence mining shortly.
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Gold losses by UKS-22M Churn Drills
Example in Mongolia
RE-DRILLING OF THE TOSON ALLUVIAL
prospect line
bore
hole
refere
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gold recovery of Churn
Drill
Churn Drill UKS-22M
Bucket Drill UBSR-25M diameter 660mm
overb
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pla
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overb
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pla
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resourc
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M M mg/m3 mg/m2 m m mg/m3 mg/m2
656
020 35.19% 0.6 8.4 58 487 1.0 7.4 187 1,384
016 43.03% 0.2 6.4 107 685 0.4 8.0 199 1,592
012 63.15% 0.3 6.7 213 1,299 0.3 8.1 254 2,057
08 42.95% 0.8 4.8 54 259 0.7 4.7 107 603
04 112.79% 0.6 5.2 139 723 1.1 5.3 121 641
0 38.42% 0.0 3.0 260 780 0.0 5.0 406 2,030
4 10.09% 0.0 3.6 6 22 0.0 3.4 64 218
8 3.35% 0.0 4.6 25 115 0.0 5.8 592 3,434
12 12.18% 0.6 5.6 18 101 0.6 5.8 143 829
16 9.76% 1.6 3.8 72 274 1.6 5.2 540 2,808
20 20.02% 2.4 4.6 179 823 2.3 4.9 769 4,111
24 1,629.07% 2.0 7.6 553 4,203 2.0 6.0 43 258
28 76.09% 2.1 5.1 116 592 2.0 4.8 162 778
32 1.55% 2.1 3.3 11 36 2.1 4.9 473 2,318
36 2.77% 1.9 4.5 8 36 1.9 4.9 265 1,298
580
14 3.61% 1.0 4.4 29 128 0.5 8.7 407 3,541
22 6.53% 1.3 4.5 28 126 1.2 7.6 254 1,930
26 69.53% 1.3 5.3 84 445 1.0 6.6 97 640
30 2.19% 1.3 3.3 10 33 1.2 6.8 222 1,510
34 11.17% 1.3 5.3 8 42 1.2 8.0 47 376
38 62.05% 1.2 5.2 56 291 1.3 6.7 70 469
42 21.37% 1.1 4.7 143 672 1.3 7.1 443 3,145
46 2.09% 1.3 4.3 4 17 1.4 6.6 123 812
50 0.90% 2.8 3.4 4 14 1.7 5.5 284 1,562
54 167.45% 3.7 4.3 662 2,845 2.6 6.2 274 1,699
58 67.33% 4.4 4.0 679 2,716 3.8 5.4 747 4,034
548
016 1.88% 1.7 6.3 9 57 1.7 11.1 273 3,030
012 147.33% 2.0 9.6 132 1,267 2.0 10.0 86 860
08 13.58% 1.8 10.2 54 551 1.8 11.4 356 4,058
04 17.13% 1.6 8.8 150 1,320 1.6 11.2 688 7,706
12k 4.05% 1.8 6.6 20 132 1.8 9.4 347 3,262
16 48.54% 2.0 9.6 192 1,842 2.0 11.0 345 3,795
average: 34.34% 1.46m 5.53m 128 717 1.38 6.98 278 2,087
(excl. 656/24):
28.15% 1.45m 5.46m 114 604 1.36 7.02 286 2,146
Figure 8: Compiled by Robin Grayson from the Mongolian State Geofund archives.
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Revised estimation of additional gold resource at Samti
At Samti, the Soviet UKC-22M churn drills proved 20.78 tonnes of placer gold (pure) considered economic, plus a further 2.1 tons subeconomic.
At Samti, if redrilled with a Soviet UBSR-25M bucket drill then the expected result would be anticipated to be an additional 57 to 79 tonnes gold, yielding an additional income of 1.8 to 2.9 billion USD.
Location Kg of gold (pure) Correction factor x2.5 Correction factor x3.5
Samti left area 3,907.3 9,768.25 13,675.55
Samti right area 16,782.8 41,957.00 58,739.80
Samti “subeconomic” 2,128.0 5,320.00 7,448.00
Gold total (pure) 20,690.1 57,045.25 79,863.35
Gold price/gram 50 50 50
Value in ground $1,034,505,000 $2,852,262,500 $3,993,167,500
In addition, following Mongolian experience, an additional 10 to 20 tonnes of gold might reasonably be expected by extensive subeconomic areas becoming economic in the same manner. It is therefore reasonable to suggest that the total placer gold in the ground is therefore in the region of up to 100 tonnes, which would probably make Samti the largest unmined placer gold deposit in the world.
Mining method and major environmental concerns
The Samti gold deposit is large and parts of it are at great depth. Open pit ‘dry’ mining should be rejected due to considerable environmental safety concerns due to:
a) The high risk of severe flooding from high river flows,
b) Even greater risk from inrush of water from gravels, and c) high risk of encouraging uncontrollable unsafe illegal artisanal mining.
The only realistic and safe method of mining this deposit is by deep dredging, by a civil engineering cutter suction dredge to strip most of the overburden, followed by a suitable gold dredge (e.g. Dutch or USA wheel dredge, Dutch or Siberian bucket-line dredge or by a modified German grab dredge).
