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BKM Copper Project - Long Column metallurgical tests confirm previous positive results

Asiamet Resources Limited ("ARS" or the "Company") is pleased to announce positive results from the column leach test work being undertaken as part of the Bankable Feasibility study on the Beruang Kanan Main ("BKM") copper deposit. 

Following a 270-day leach cycle, metallurgical results obtained from the long column (6-metre) programme, support the results previously reported in the short column test work (refer ARS news release 19 December 2017).  Results confirm the design basis being utilised for the leaching, solvent extraction and electrowinning facilities and provide critical process plant design inputs for the BKM feasibility study.

Key highlights include:

  • Soluble copper recoveries from the coarse crush size (P80=19mm) ranged from 72% to 81% (%Cusol) for the dominant material types      defined at BKM.  These recoveries represent a 4% improvement, on average, over the recoveries obtained from the short column              programme.
  • The long column results confirm the expectation that utilising a finer crush size will deliver recoveries of 80% to 85% (%Cusol) for the      dominant material types, as observed in the short column programme.
  • The majority of the soluble copper, as determined by the sequential copper analysis, was recovered.  The soluble copper present in        the residual (post-leaching) material for most columns was less than 0.15% Cusol.

 

Background

Asiamet completed a 122-hole Resource evaluation drilling programme as part of the BKM Feasibility Study.  The results of this Resource evaluation were announced on 28 June 2017, with a supporting technical report filed with SEDAR on15 August 2017. 

As part of this programme, several holes were drilled throughout the BKM deposit to collect representative samples of various material types and grades for detailed metallurgical test work.  From these samples, six composites were prepared and a total of 20 columns, comprising 12 short columns (2-metre) and 8 long columns (6-metre), were operated at the CORE Resources laboratory, in Brisbane, Australia.  Figures 1 and 2 show the loaded short and long columns at the start of the leaching programme. Results from the short column programme were reported on 19 December 2017.  

Copper recoveries from the short and long column test work programme are in line with expectations and confirm that the copper minerals in the BKM deposit are amenable to heap leaching.  Table 1 summarises the results for each of the columns. 

The long columns predominantly tested material at the coarse crush size (P80 of 19mm). However, based on the leach column performance to date, and supported by preliminary geotechnical and hydrodynamic studies currently being undertaken (HydroGeoSense metallurgical test work programme), the finer crush size (P80=12.5 mm) is the preferred design basis for the BKM Copper Project.

The long columns achieved a leach solution flux of 4 to 6kL/tonne.  This leaching efficiency is generally in line with results achieved in secondary copper sulphide, heap leach operations globally.  Acid generation characteristics exhibited in the long columns indicate a neutral to low acid generating environment (<5kg/t) is likely over the leach cycle, which provides a positive basis for lower operating costs.

 

Ongoing Metallurgical Testing

The leach column test work provides key design criteria for the leaching, solvent extraction and electrowinning facilities that will be designed as part of the BKM Feasibility Study.  The outcomes are also a key input into the mine optimisation and project evaluation elements of the study.

An additional round of column test work is being undertaken to provide further information to support production optimisation and value improvement activities for the BKM Copper Project.  This additional test work will also provide key input data for ramp-up and early mine life stages of the operation.   

The detailed chemical characterisation from the leaching test work programme, when combined with the hydrodynamic testing programme, which is being conducted at the world leading HydroGeoSense (HGS) facility in Arizona, will provide critical information for the BKM Feasibility Study and to establish the leach recovery targets for the operation.  Metallurgy data generated from both programmes will allow the project team to develop a robust and optimised set of design criteria for the heap leach pads and overall process engineering work.

 

Peter Bird, Asiamet's Chief Executive Officer commented:

"Results of the long column test work provide critical process plant design inputs for the BKM feasibility study and as such it is very pleasing to report results that are in line with our expectations and that further improvement in recoveries is anticipated from applying finer crush size.  The Feasibility Study remains on track for delivery by the end of H1 2018 and we will continue to communicate ongoing results as they become available.  The BKM Project remains extremely well positioned as one of the few advanced new copper projects moving towards production against a backdrop of a projected net short supply balance and rising copper prices."

 

 

Table 1: Short and Long Column Leaching Recovery Summary

 

 

 

Column ID

Column Length

 Crush Size

(P80)

Recalculated Head

(%CuTot)

Recalculated Head Soluble

(%CuSol)

Total Cu Recovered (%)

Soluble Cu

Recovered

(%)

1

2-metres

12.5mm

0.48

0.37

68.8

88.5

2

2-metres

19mm

0.51

0.39

62.0

81.5

3

2-metres

12.5mm

0.58

0.36

49.3

79.4

4

2-metres

19mm

0.54

0.33

45.4

72.9

5

2-metres

12.5mm

0.66

0.53

70.2

86.4

6

2-metres

19mm

0.57

0.46

58.6

73.8

7

2-metres

12.5mm

0.75

0.54

55.7

76.9

8

2-metres

19mm

0.69

0.51

51.6

69.8

9

2-metres

12.5mm

0.75

0.60

65.5

82.1

10

2-metres

19mm

0.76

0.58

55.6

72.4

11

2-metres

12.5mm

0.38

0.33

62.4

73.3

12

2-metres

19mm

0.35

0.30

57.2

66.8

13

6-metres

19mm

0.46

0.35

59.9

79.0

14

6-metres

19mm

0.59

0.39

49.7

75.5

15

6-metres

19mm

0.64

0.52

66.8

81.3

16

6-metres

19mm

0.79

0.57

53.9

73.9

17

6-metres

19mm

0.75

0.60

58.6

73.3

18

6-metres

19mm

0.76

0.61

58.9

73.1

19

6-metres

12.5mm

0.37

0.32

60.2

71.6

20

6-metres

12.5mm

0.35

0.30

63.3

74.3

 

 

 

Notes:

All columns were 150 mm in diameter

Assays were completed for the residual material from the six (6) long columns.  The detailed diagnostic analytical procedures, including sequential copper assays developed for the BKM mineralisation, has allowed for head grades to be verified through mass-balance calculations for each column.  These calculations have been utilised to evaluate recoveries of total copper (%CuTot) and soluble copper (%Cusol) for each column. 

 

Figure 1: Short Columns loaded and under leach at CORE Laboratory. To view the image, click on the following  link http://www.asiametresources.com/i/misc/2018-02-28_NR-Fig1.jpg

Figure 2: Long Columns being loaded at CORE Laboratory. To view the image, click on the following link    http://www.asiametresources.com/i/misc/2018-02-28_NR-Fig2.jpg

 

 

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