Namibian Resources Plc was incorporated in January 2001 and achieved a listing on the AIM of the London Stock Exchange in March 2004.

The Company, which operates through its 100% owned subsidiary Sonnberg Diamonds (Namibia)(Pty) Limited, holds a contract from NAMDEB Diamond Corporation (Pty) Ltd for the prospecting and mining of diamonds within the Pomona concession in the Luderitz District of Namibia. The concession area covers an area of about 120 square km (12,000 ha), and the Company is authorised by NAMDEB to prospect and mine in certain defined areas within this concession.

Namibian Resources aims to use the funds raised from the listing to increase annual production from the current level of 2,900 carats/year to 7,500 carats and then on to 15,000 carats/year.

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Very difficult to find information on this company as they do not even have a home page, friends of mine feel the annual production levels are greatly under estimated and we could see a huge up side to this company before Christmas 2004. The new equipment they are using looks promising.



http://www.mining-investor.com/

Hi dexter.

Sunny diss is cold & foggy diss at the moment. Ive been unfortunate thet I have to give up my job & am on the sick for a short time but it is great that I can do research & keep an eye on the shares all day where as before I was working from 6 till 6. As with PET, I sold half my holding at 130p so got some profit, im holding the rest to see what happens. Bought into sibr earlier today.

wilbs

Got sent some reports from NBR today will have a look at them tomorrow as it is a bit late tonight, will post the best bits from them if people are interested, the engineering report is 35 pages long, so not really something I can put on the BB, Dexter I'll send you a copy via e-mail.

Tokyo

Tokyo,

Cheers, look forward to that.

Morning Campers, just about to get started on these NBR reports.

will report back later, Here is the contents page, perhaps if you want to see certain parts just ask and I'll try a cut & paste, as the report is too big to post here.

Tokyo

CONTENTS.


Summary 4

1. Introduction 6
1.1 Project situation 6
1.2 Conceptual approach 6

2. Type and nature of diamond deposits in the concession 8
2.1 Type of deposits 8
2.2 Nature of deposits 8
2.3 Diamond content 10

3. Resource base 12
3.1 Current resource statement 12
3.2 Development potential 14

4. Mining 15
4.1 Introduction 15
4.2 Basic mining system 15
4.3 Bedrock surface cleaning 15
4.4 Equipment required 16
4.5 Tailings dumps 16
4.6 Stockpiles 17

5. Processing 18
5.1 Feed preparation 18
5.2 Diamond concentration 19
5.3 Diamond recovery 20
5.4 Equipment required 20

6. Security 22
6.1 Introduction 22
6.2 Regional security 22
6.3 Plant security 22
6.4 Costs 23

7. Water supply 24
7.1 Introduction 24
7.2 Plant operations 24
7.3 Human consumption 26

8. Prospecting and exploration 28
8.1 Deposits of interest 28
8.2 Sampling methods 28
8.3 Volumes to be sampled 29
8.4 Sample distribution 30
8.5 Sampling equipment 30
8.6 Processing 30
8.7 Costs 30

9. Environmental considerations 32
9.1 The general environment of the Pomona concession 32
9.2 Sonnbergs environmental responsibilities 33

10. Investment required for development 34
10.1 Investment required 34

References 35

morning tokyo,sorry afternoon
got the e-mail and attachment, but it would`nt open in outlook express, could you possibly send it again and i`ll try to open it in yahoo,
it should prove interesting reading.
cheers,
dexter

dexter - just sent it again

Here is the summary from the 1st report, bit busy today, so thought I'd post parts 1-5 of the report, so others can read it, probably won't be able to see graphs.

SUMMARY.


The present report presents a programme for the development of Sonnbergs Pomona concession where it is prospecting and mining for diamonds under contract to NAMDEB, the mining licence holder. Sonnbergs contract endures until April 2012 and contains a provision for an extension for a further 10 years after that date. Sonnberg has been mining in the Pomona concession since 1992 with an average annual output of around 2,900 ct.

The present development programme has a capital budget of approximately US$2.4 million (1.4 million) and is planned to raise the Sonnbergs annual output to around 100,000 m3 (180,000 t) per year, equivalent to a diamond production level of between 7,500 and 15,000 ct/yr, depending upon the order with which the identified diamond-bearing deposits are brought into production. It is anticipated that revenues will increase to between US$1.1 million and US$1.5 million per year.

An integral element of the development programme is that Sonnberg must vigorously pursue a prospecting programme. The objective is to quantify the diamond resources contained within the over 2 million m3 of known diamond-bearing material which cannot at present support an estimate of contained diamond resource. Wider exploration within the concession is also envisaged. Provision is made in the capital budget for the first two years of prospecting.

The diamond-bearing deposits in the Pomona concession occur within thin, sheet-like, loose, gravely sands resting in the bottom of a series of valleys. There is little or no overburden. Mining is therefore a relatively simple operation which can be carried out by a front-end-loader, occasionally assisted by a bulldozer. The generally low-gradient bedrock surface lends itself to cleaning either by sweeping or by scraping. Deposit transport is by 20-t articulated dump truck.

Hitherto most of Sonnbergs processing has been dry. However, not all deposits are amenable to dry screening and it is proposed that Sonnberg move to all-wet processing of material. This will lead to a much better particle separation on the screens and corresponding better diamond recovery. It is therefore necessary to provide a regular water supply. This is most capital- and operating-cost effectively done by establishing a pipeline to pump water from Jammerbucht to a reservoir at the watershed west of Pomona village at the head of Idatal. From there, water can be supplied by gravity feed through to the southern part of the concession where the greater part of the known diamond resources exist.

Diamond recovery, based on the use of Pleitz jigs, in Sonnbergs operations to date has been highly inefficient. It is proposed to move to the use of Dense Media Separation (DMS) technology, the standard in the wider diamond industry. Two 10 t/hr DMS units will provide the capacity for the envisaged rate of production. It is proposed to use two small units to provide greater flexibility in operations given the wide scatter of relatively small individual deposits in the concession. An increase in plant operating costs is compensated by reduced trucking costs.

Final diamond recovery will be by X-ray technology allied to diamond-picking in a glove box.

Sonnbergs operations come within the NAMDEB security umbrella which provides regional access control with the potential for searching using, where appropriate X-ray technology. Sonnberg also has its own security staff and all operations involving handling diamonds are covered by CCTV.

Sonnberg is contracted to adhere to NAMDEBs Environmental Management Programme which requires active environmental protection measures during operations as well as ground rehabilitation following completion of operations in any given part of the concession.


1. INTRODUCTION.


1.1 PROJECT SITUATION.

Sonnberg Diamonds (Pty) Ltd, a 100%-owned subsidiary of Namibian Resources plc, holds a contract to prospect and mine for diamonds in the 120-km2 Pomona concession, which is part of a larger mining licence held by the NAMDEB Diamond Mining Corporation (Pty). Sonnbergs contract endures until April 2012 and contains a provision for an extension for a further 10 years after that date. Sonnberg Diamonds and its predecessor company Sonnberg Diamante (Pty) Ltd, have been mining in the Pomona concession since 1992 with an average annual production of around 2,900 ct and a peak annual production of around 5,500 ct.

Namibian Resources wishes to invest in Sonnberg with a view to increasing diamond production and placing the operations on a technically superior basis. The objective of this report is to outline an appropriate method of mining and processing the diamond deposits in the Pomona area, due regard being given to the terms and conditions of the contract with NAMDEB.


1.2 CONCEPTUAL APPROACH.

Diamond production from the Pomona concession is a relatively simple operation. However, there are many ways in which it can be carried out in the context of a small mine all of which have various advantages and disadvantages. Based on knowledge of the deposits, Sonnbergs operations to date, and prior experience elsewhere, the following concepts have been applied in outlining the programme for the development of the concession.

Redundancy in equipment provision. Sonnbergs operations in the past have been greatly hindered by the break-down of single pieces of equipment which occur at critical links in the production chain. Such breakdowns are always likely in the context of a small mine operating in a harsh environment. To the greatest reasonable extent possible, a degree of redundancy should be designed into the provision of equipment as well as the mine plan itself. Thus, for example, rather than purchase a single 30-t haulage truck, it may be better to purchase, say, two 15-t trucks. This will increase capital expenditure but at the long-term gain of more uniform production.

More than one working face. Mining in the Pomona concession is characterised by a large number of relatively small mining areas (including former dumps) each of which has a distinct character in terms of diamond grade and value. Production, both in terms of caratage and revenue, can therefore vary very substantially from time to time even if the volume of material being processed is uniform. In such circumstances it is good practice to source production from a number of areas at the same time, thus reducing overall variability in revenue. Such an approach leads to easier overall management of the mine. It is therefore considered that Sonnberg should plan to have three or four areas in production at any one time.

Make of equipment. Currently Sonnberg, through inheritance and occasional purchase, has a range of different makes of equipment Caterpillar, Bell, Fiat-Hitachi, etc. It will represent a significant saving in spare part and maintenance costs to use a single make of equipment, to the greatest extent possible. Therefore over a period of time, through necessary new purchases, Sonnberg should begin to consolidate its equipment on a chosen limited number of makes.

Wet vs dry processing. The current Sonnberg processing plant is essentially dry with the exception of the final concentrate production in the Pleitz jigs. Dry processing of gravels is typically more inefficient that wet processing and results in a much poorer diamond recovery. Certain of the diamond-bearing material in the concession is also damp and tends to blind dry screens. In the past this material was treated by Sonnberg using a diamond pan plant. Overall, there are clear advantages to Sonnberg in establishing a wet process plant.

Stockpiles. Running of a plant at or near its capacity on a small mine is made much easier where a stockpile or stockpiles are operated at the plant. This means that down-time in mining or haulage does not have the immediate effect of bringing production to a stand-still. Similarly mining can still proceed during down-time at a plant. Stockpiles for each mining area in production should therefore be established in the immediate vicinity of the plant.

Realism in the capacity of a small mine. For a range of reasons small mines productivity is normally less than in large mines. It is therefore necessary to be realistic as to the likely rate of working at a small mine. The present programme therefore has been designed so as not to attempt to make maximum utilisation of either time or equipment.

2. TYPE AND NATURE OF DIAMOND DEPOSITS IN CONCESSION.


2.1 TYPE OF DEPOSITS.

The geological occurrence of the diamond deposits present within the Pomona concession has been described previously (Sutherland, 2003). In summary, diamonds are known to be present in the following types of deposits.

Untouched original in-place deposits;

Areas previously mined but where there is a thin veneer of material resting on bedrock which requires mining by bedrock sweeping or scraping;

Areas previously mined that are covered by the waste material left following dry field screening of the original deposit;

Tailings dumps.

Table 1 summarises the volumes of diamond-bearing material that are presently estimated to be in each type of deposit. A more detailed breakdown of their estimated diamond content is given in Sutherland (2003) and a summary is included in Section 3 of this report.

Table 1: Volumes of diamond-bearing material identified in the Pomona concession.

Type of deposit Volume(m3)

In-place deposits 630,000
Bedrock sweeping deposits 36,000
Previously mined areas (resampled) 36,000
Previously mined areas (unsampled) 1,166,000 1,273,000
Tailings dumps 743,000

Total 2,611,000 2,718,000


2.2 NATURE OF THE DEPOSITS.

The undisturbed diamond deposits in the Pomona concession almost everywhere consist of a loose gravely sand resting directly on the valley-bottom bedrock surface. In certain valleys there are carbonate-cemented horizons within the diamond-bearing sediments. In valleys that have been previously mined, the diamond-bearing material consists of waste from in situ dry sieving whereby the over- (+8 mm) and under-size (-1.6 mm) material rests on the valley floor in a series of small, roughly conical mounds. These mounds consist of loose, gravely sand or sandy gravel. From the point of view of mining, there is little to distinguish such material from the undisturbed deposits.

2.2.1 Sediments.

No significant overburden occurs and the full thickness of sediment resting on bedrock is targeted for excavation. In certain locations it may be advantageous to bulldoze the upper approximately 10 cm of sandy material, particularly where it consists of small dunes gathered around vegetation tussocks. This both removes an essentially barren layer of mobile fine to medium sand and reduces the amount of vegetation passed to the screening plants. Where abundant such vegetation can reduce the effectiveness of the screening process.

The deposits are essentially thin sheets whose dimensions in plan are one to two orders of magnitude greater than their thickness. Average deposit thicknesses range from less than 5 cm to a maximum of 1.27 m. Maximum deposit thickness ranges up to around 2.5 m but thicknesses over 1.5 m are quite localised. Figure 1 shows the frequency of the average and maximum sediment thicknesses for the deposits identified as containing diamond resources in Sutherland (2003).

Figure 1: Histograms of average and maximum sediment thickness in the diamond bearing deposits of the Pomona concession.


2.2.2 Bedrock surface

The nature of the bedrock surfaces on which the deposits rest largely reflects the lithology and structure of the underlying rocks which can be categorised as three principal types (Sutherland, 2003) granite gneisses, clastic metasediments and chemical metasediments. Much less frequent are the occasional igneous intrusions encountered although these can present locally sharp relief features. Weathering-resistant silicified sediments are also occasionally present on the tops of a number of hills. Such flat-topped hills can be a prominent part of the local scenery but have only a minor relationship to the diamond deposits.

Three broad hardness characteristics for the bedrock can be identified and these are related to the bedrock lithologies (Table 2).

Table 2: Relationship between exposed bedrock hardness and bedrock lithology.

Hard, unweathered to lightly weathered Firm, weathered Soft, decomposed
Granite gneiss Yes Yes
Clastic metasediments Yes Yes
Chemical metasediments Yes


Underlying the deposits on the valley floors the bedrock relief is generally gentle. Locally, however, moderate to high relief elements occur. The higher relief elements, which may locally acts as traps for diamonds and also pose difficulties for excavation are a consequence of the following factors (Table 3).

Table 3: Causes of higher relief elements in different rock types in the Pomona concession.

Cause of relief elements Granite gneiss Clastic metsediments Chemical metasediments

Differential weathering of joints Yes
Differential erosion or weathering of strata Yes Yes
Differential erosion of intrusive rocks Yes Yes Yes
Fluvial erosion of bedrock (minor and moderate sized channels) Yes Yes
Aeolian erosion of bedrock Yes Yes Yes


The distribution of the various bedrock relief elements has not been systematically mapped in the concession. However, it may be stated that the relief elements caused by intrusive rocks and both fluvial and aeolian erosion are essentially local. The differential weathering of the joints in the granite gneisses appears to form areas with dimensions of some tens of metres of higher relief. Erosion or weathering of strata, particularly in the areas underlain by clastic metasediments can, however, be areally extensive. Such bedrock relief is widely found, for example through Hexenkessel. In such areas it creates a significant difficulty to mining and ensuring that the bedrock surface is cleared of all diamond-bearing material.


2.3 DIAMOND CONTENT.

The Pomona area was made famous by the diamond concentrations on the ground surface from which diamonds were picked up by hand. However, the remaining deposits are much lower in grade and have diamonds distributed throughout the greater part of the thickness of sediment present. There is some evidence for diamond distribution within the deposits being affected by the specific processes such as ephemeral stream activities or aeolian activity by which the deposits were formed or modified. However, the typically very thin sediments militate against any attempt to selectively mine the deposits in a vertical sense. Deposits are sub-divided in plan, but in almost all areas encountered the full thickness of sediment present must be regarded as diamond-bearing from a practical mining point of view.

3. RESOURCE BASE.


3.1 CURRENT RESOURCE STATEMENT

The diamond resources identified in the Pomona concession (Sutherland, 2003) have been summarized in Table 4.

Table 4: Classification of identified diamond resources in the Pomona concession.

Resource category Volume(m3) Grade*(ct/m3) Diamond resource*(ct)

Measured 0 0 0
Indicated 666,200 0.053 35,500
Inferred 428,200 0.064 27,550
* Based on minimum screen size of ca. 1.6 mm.


The resources identified in Table 4 relate to 45 separate deposits or sections of deposits, the details of which can be found in Sutherland (2003). Figures 2 to 4 shows the distribution of the deposits within the concession according to volume, contained carats and contained value.


Figure 2: Distribution of identified deposits scaled according to volume (m3).


Figure 3: Distribution of identified deposits scaled according to contained resources (ct).



Figure 4: Distribution of identified deposits scaled according to contained estimated value (US$).

Examination of Figures 2 to 4 reveals that the identified deposits occur throughout the west and central part of the concession. As noted elsewhere (Sutherland 2003), this partially reflects the original occurrence of the diamonds but also reflects the lower level of exploration in the eastern portion of the concession. There is a concentration of identified deposits in the southern part of the concession which is most notable in the contained diamond resources but is also where the bulk of the contained value resides.

The resources in Table 4 have been categorized in accord with the SAMREC Code. In such a formal scheme it is not possible to incorporate the large volumes of probably diamond-bearing ground that exist within the concession but for which there are no actual sampling results. Notable among this type of ground are the more than 1 million m3 of waste deposits in previously mined areas and the 120,000 m3 of material in the PDG/CDM tailings dumps (excluding the Kaukausibtal dump which is assessed as an inferred resource). It is known on the basis of analogy with similar deposits in the concession that both these types of material contain diamonds but in the absence of direct sampling information it is not possible to place any form of estimate as to their diamond content.


3.2 DEVELOPMENT POTENTIAL

There is substantial potential for Sonnberg to increase the formally stated diamond resources in the concession. Such an increase can come from sampling of the probably diamond-bearing deposits mentioned in the previous paragraph. It is also likely that exploration in areas that have hitherto only been lightly sampled or not sampled at all will result in the discovery of additional diamond resources. It will therefore be necessary for Sonnberg to carry out a prospecting programme in order better to quantify the inferred resources and to permit estimation of the diamond resources that are likely to exist in the other deposits (see Section 8).









4. MINING.


4.1 INTRODUCTION.

The deposits to be mined are thin sheets of gravely sand generally resting on a firm bedrock surface. No overburden occurs in any of the identified mining areas. Surface vegetation consists of isolated tussocks of grass and other plants around which loose, wind-blown sand may have accumulated.

Typically, the whole thickness of loose material above the bedrock contact is to be mined. Locally it may be advantageous to bulldoze the surface vegetation as this can bind on screens and result in slower processing. In general, however, this is not a major problem and cannot be usefully practiced where the deposit it too thin.


4.2 BASIC MINING SYSTEM.

The basic mining system practised by Sonnberg is either to excavate directly from a working face by a front-end loader or to use a bulldozer to push the deposit into windrows which can then be excavated by front-end loader. The choice between the two is a practical function of the thickness of deposit and the overall geometry of the mining area. Generally, the bedrock is sufficiently resistant that little of it is excavated in this approach, hence limiting dilution. Locally, however, there are certain areas where decomposed bedrock underlies the mining horizon and care must be taken in such areas to avoid overmining.

Mining block preparation is minimal, requiring only the limits of the area to be mined to be identified on the ground and an access track to be bulldozed to the site.

The excavated material is removed from the mine site to the processing plant by dump trucks. For the majority of the period of its operations, Sonnberg has transported the all the mined material from the mining block to the processing plant. More recently, it has deployed a field screening plant, with on the 8+1.6 mm size fraction being transported to the processing plant. This reduces the amount of material being hauled to between 10% and 30% of the original mass, thus significantly reducing haulage costs. There are no additional screening costs, but there is additional material handing by the front-end loader at the mining block. To date, this additional material handling at the mine site has been within the capacity of a single front-end loader being used both to feed the field screening plant from the working face, to load the dump trucks with sized product and to stack the rejects from the screening plant.


4.3 BEDROCK SURFACE CLEANING.

In the past, Sonnbergs mining practice has been rather poor and significant thicknesses of deposit have been left as a thin layer resting on bedrock. This material is diamond-bearing and should be mined (Sutherland, 2003). More recently, this has been done by Sonnberg using either a bulldozer carefully to scrape the bedrock surface or a heavy-duty street sweeper (Moro 4200) to brush the surface.

The Moro has proved itself to be very effective in cleaning hard, low-relief bedrock surfaces of material that is essentially dry. Where bedrock irregularities occur, however, the Moro does not have sufficient ground clearance. In addition, damp material tends to clog in the suction system which must be cleaned out with consequent down time. There are therefore certain sections in which the Moro cannot therefore work. In such areas it is necessary to use a bulldozer to scrape the bedrock surface clear.


4.4 EQUIPMENT REQUIRED.

On the basis of the mining system outlined above the equipment requirement is summarised in Table 5.

Table 5: Equipment required for a single mining block.

Equipment Capacity Use

Bulldozer D6-D8 Block access; possible removal of surface vegetation; possible production of windrows; possible bedrock scraping.
FEL 2 m3 bucket Mining from face or from windrows; possible feeding field screening plant; loading dump trucks with screened product; redistributing screening plant rejects.
Dump truck(s) 20t Transport of deposit to processing plant
Moro? Possible final bedrock sweeping.


On the assumption that the maximum distance from a process plant that material will be sourced is 2 km, a truck cycle of load transport dump return to working face is considered to be 40 minutes. A 20 t truck will therefore have a transport capacity of 30 t/hr. The required rate of feed to one of the DMS plants is 40 t/hr, hence each mining team for a DMS plant will require the availability of two 20-t trucks.


4.5 TAILINGS DUMPS.

There are ten tailings dumps aggregating over 500,000 m3 of diamond-bearing material in the Pomona concession. Their sizes range from 14,000 m3 to almost 115,000 m3. The diamond content and process characteristics of these dumps requires sampling in order to determine the extent of diamond resources contained within them. However, at the estimated rate of working, a single 10t/hr DMS plant will have sufficient material in each dump for a minimum of several months work up to a possible two years work in the largest, should all the material justify reprocessing.

In such circumstances it will be operationally advisable to establish the DMS plant in close proximity to the dump being treated and a very simple mining system using a FEL to load a conveyor feeding directly to the diamond recovery plant will be possible. Such a system will significantly lower operating costs by removing the costs of trucking. Implementation of such a system will, however be dependent upon sampling results from the dumps.


4.6 STOCKPILES.

There are a number of advantages to operating a stockpile system at the diamond recovery plants.

Modulation of the flow of material to the plant, reducing the interdependence of the mining and processing aspects of diamond production. This will ensure less down time in the whole operation.

Allows the mining teams, during a relatively short period of time, to supply the plant with material from more than a single mining face. This leads to more uniform production in terms of both the quantity and quality of diamond being produced.

Permits material from the sampling programme to be integrated into the processing schedule at the plant and hence obviates the need for a separate diamond processing plant for the exploration and prospecting team.

For these reasons Sonnberg should establish clearly demarcated stockpile areas adjacent to the process plants and ensure that stockpiles are built up in advance for the start of processing material from any given deposit.

5. PROCESSING.


5.1 FEED PREPARATION.

The Sonnberg contract states that Sonnberg must process the 8 +1.6 mm fraction of the material mined. On the basis of historical reference and measurements by Sonnberg, approximately 20-25% of the in-place deposit falls within this size range.

The majority of the deposits encountered in the concession are essentially dry. However, in a number of areas in basinal sections of valleys where salt pans exist or where water may pond following rare heavy rainfall events the deposits may be damp and/or have a higher clay content which tends to retain moisture derived from mists and fogs. Such deposits are encountered, inter alia, in Idatal (particularly in the south), lower Scheibetal and Saltztal. Coincidentally, many of the areas where such deposits are found also have above-average diamond sizes and hence correspond with some of the high value deposits.

Dry screening of the majority of the dry deposits is feasible and has been carried out by Sonnberg for much of its work. Periods of rain, however, can result in disruption to production as the damp sand and gravel tends to blind the screens. In normal conditions it may take 1-2 days for the ground to dry out sufficiently for production to restart.

Dry screening, however, cannot effectively be applied to damp ground. A notable demonstration of this is the prospecting results from the high-value Salztal deposit. Initial prospecting by the Deutsch Diamanten Gesellschaft in 1917 recovered 0.016 diamonds per m2 sampled with an average size of 0.32 ct/st. This deposit was re-sampled by CDM in 1956 because the material within the salt pan is damp and treatment of such ground is known to have been problematical to the German prospectors (Corbett, 1986). CDM recovered 0.06 diamonds per m2 sampled with an average size of 0.59 ct/st. The initial prospecting did not seem to indicate the presence of an economic deposit, the re-prospecting demonstrated the presence of a highly attractive one with three times the diamond frequency and almost twice the stone size.

Wet processing of gravels from certain parts of the concession is therefore obligatory. For the remaining parts of the concession it is preferable given that wet screening is normally more efficient in providing good particle discrimination than dry screening.

The prime reason that Sonnberg has preferred dry screening is that the deposits they have been treating have been several kilometres from the coast and they have not been able to invest sufficiently to ensure a regular water supply of sufficient volume to permit all-wet processing. This issue is discussed in Section xx where it is concluded that the installation of a pipeline to feed process plants along Idatal and in southern Hexenkessel and Scheibetal is quite feasible with relatively modest capital investment.

It is therefore considered that it is preferable for Sonnberg to move to all-wet screening of deposits.



5.2 DIAMOND CONCENTRATION.

There are three basic approaches to diamond recovery that may be considered for Sonnbergs operations.

Diamond pan. A diamond pan has a good capital cost to throughput ratio. However, pans are relatively inefficient for diamond recovery, particularly for smaller diamonds that make up a significant part of Sonnbergs resources. Because certain types of deposit cannot be treated effectively by dry screening, Sonnberg used a pan plant when working in lower Idatal. However, this did not function very efficiently as indicated by the diamond content of the resulting tailings dump.

Jigs. Currently Sonnberg has a small plant based around a batch of Pleitz jigs. These have very low capital cost but very limited throughput. Moreover, unless operated carefully (which argues against their use in production situations) they are inefficient at diamond recovery. It is known that at times in the past Sonnberg appears to have been losing as much as 40% and possibly over 50% of the original, recoverable diamonds from certain of their small-stone deposits. In addition to their low capital cost, a major advantage of a Pleitz jig is that it has a very low water requirement. It is possible to adopt a larger type of jig (such as the Dobson) where there is continuous feed. Such jigs, with appropriate handling, are significantly more efficient in diamond recovery than are Pleitz jigs. However, they also require a much greater water supply, which is their principal restriction on use in an environment such as the Pomona concession.

Dense media separation (DMS). DMS units are the norm for all industrial-scale diamond mining operations. They have been established as the most efficient means of diamond recovery, irrespective of diamond size. They also lend themselves to closed-circuit working with additional security benefits.

Of the three possible systems, DMS is undoubtedly most appropriate as, properly operated, it gives the highest rates of diamond recoveries across the full range of diamond sizes.

On the basis of the currently known resources, a production rate of approximately 100,000 m3 (180,000 t) per year would appear realistic for Sonnberg. With an effective 2,400 hours of operation in a year, such a rate of production could be attained by a 20t/hr DMS unit. However, it is considered that two 10 t/hr DMS units would be preferable. This is because two plants would give:

Greater flexibility in operations. The two units can be placed rather closer to individual deposits or groups of deposits, hence reducing overall trucking distances.

Redundancy in equipment provision. With two units there is a much lower possibility of a complete loss of production due to plant down-time.

Increased numbers of blocks in production at once. By locating the units in different parts of the concession, it is more economical to have a number of deposits in production at the same time. With, say, each plant being fed from two separate deposits, four mining faces could be in production simultaneously.

Each DMS unit can be trailer or skid mounted in order to facilitate transport.

Progressive introduction of each unit is preferable from a management point of view.


5.3 DIAMOND RECOVERY.

Currently, Sonnberg recovers its diamonds by open hand-picking from the concentrate produced from the Pleitz jigs. It is contracted to move to a hands-off form of final diamond recovery. In practice this implies the use of an X-ray system of diamond selection from a concentrate feed followed by diamond picking within a sealed glove box.

Use of a Flowsort X-ray diamond separation machine, adapted for use with a sea-water supply is appropriate. The size range of the feed is 8+1.6 mm and a single Flowsort machine is capable of handling this. The capacity of a single machine for the type of material being processed in the Pomona concession is likely to be in the range of 500-1000 kg/hr of concentrate from a DMS. Such a machine has a relatively low power requirement of 3 kVa. A water supply of approximately 15 l/min (900 l/hr) is required.

No direct figures are available for the weight of concentrate from the Pomona deposit, although for the greater portion of the concession, the concentrate is very light. In certain areas a heavier concentrate is observed where there are outcrops of gossanised bedrock. From experience elsewhere, the rate of DMS concentrate production from alluvial deposits with a light concentrate is in the region of 0.5-1.0 kg/100 m3 run-of-mine plant feed. Sonnbergs current planned run-of mine rate of production is 44 m3/hr which would imply a rate of DMS concentrate production of 22-44 kg/hr. This is well within the capacity of a single Flowsort machine.

Product from the X-ray machine should initially be collected in a sealed bin the contents of which can be fed into a glove box for separation of diamonds (which should be placed in a locked container and the remainder of the concentrate which should be placed in a separate, locked container for re-cycling through the X-ray machine.

Use of a single Flowsort machine but two DMS units means that the final diamond recovery site will be located away from one or both of the DMS units.


5.4 EQUIPMENT REQUIRED.

The equipment required for each diamond recovery plant is as follows (Table 6).

Table 6: Equipment required for each diamond recovery plant.

Equipment Capacity Use

DMS unit 10 t/hr Production of diamond-bearing concentrate
Feed preparation unit 40 t/hr Reduction of plant feed to 8+1.6 mm DMS feed
FEL 2 m3 bucket Loading plant, distributing tailings
Generator 75 KVa Power source
Pick up Service plant


In addition to the above, a single Flowsort unit, model XR 2/19W SEA will be required.

Well Tokyo and Dexter now that I have sorted out the emotional dumping process of PET and looked into this with the past posts, I can't resist puting a small amount in and see what happens. Hope you both have a good festive drink and take care. Got loads of fingers crossed that things go well,

watcher

thanks watcher,
i`m debating whether to put a smallish amount in, reading the report that tokyo posted it does seem relatively straightforward compared to PET. tokyo does put in some excellent research.
are you signing off now for the christmas period?, if you are have a good one.
dexter

Welcome to the NBR club Watcher, thankfully this one is a lot less risker than the previous one. Will try to get through these reports in the next couple of days and report back anything of interest
even got sent another one today
Tokyo

Tokyo,
You should have mail!,
dexter

just skimmed over the reports and things look like the NBR are forward planning which means growth to me. It is nice to be in a club that knows the PET history and what can go on (wrong or right) I still have a small holding. My PC is on upto friday, when I shall pop (race) out and get the misses her christmas present. I will take her out christmas eve, for lunch with some mates to talk over the year. Many PET fan's are planning to get together maybe NBR future fans. We wish you both a calm festive break and obviously a prosperous new year.

watcher ps. if all goes well my xmas bonus goes into NBR in jan.

Well gentlemen, don't want you to think I'm stalking you 'round the bb, but I've joined you in this one as well. Shame about the result across the way, but thems the breaks...appreciate all the work and research you guys put into the thread.
I like the look of this one and Jan isn't long to wait before the work begins. Maybe we can't win them all, but we can certainly win quite a few!

Its nice to see a few familiar names on this one. Has anyone got an sp as to what it may goto in mind? I think I may reduce my PET holding again and do a Toyko and topup.

wilbs

Wilbs I have a target price of 100-120 pence, and this time I shall not be greedy and let it run, I'll be coming out with profits and top slicing this one.

Tokyo

Hi Tokyo.

I think we all learned from PET. I was glad I top sliced and came away with a profit but I was reluctant to as greed took over and I wanted to make more money. Im gonna sell the rest of PET today as my belief in them has somewat dropped. Their future looks ok but I can make elsewhere. Gonna topup here & sey.
Are the markets open tomorrow?

wilbs

markets are open until 12.30 tomorrow

LSE Timetable
23 Dec Normal
24 Dec Close 12:30
25 Dec Closed
26 Dec Closed
27 Dec Closed
28 Dec Closed
29 Dec Normal
30 Dec Normal
31 Dec Close 12:30
1 Jan Closed
2 Jan Closed
3 Jan Closed
4 Jan Normal