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APPLICATION NOTE

Copper-Gold-Silver Concentrate – OREAS 990B

SUMMARY

This application note is for the digestion of OREAS-990B, a Copper-Gold-Silver Concentrate.

Instrument:

ColdBlock CB15S sample digester technology, chiller, ICP-OES, ICP-MS

Published:

August 2022

Digestion Time:20 Minutes
Acid Used:Reverse Aqua Regia
Average ColdBlock Recovery vs. CRM:

  •  95% Copper 

  • 99% Gold

  • 99% Lead

METHODOLOGY

  1. Chiller temperature was set to -5°C
  2. 0.25g of OREAS 990b was weighed and placed into a ColdBlock Digestion vessel
  3. 20mL of Reverse Aqua Regia was added (HNO3 is added first, followed by the HCl) (For elements requiring Hydrofluoric Acid 20mL Reverse Aqua Regia + 3mL HF was added)
  4. Sample was digested at 80% power for 20 minutes
  5. Sample was cooled and bulked to 50mL using 2% HNO3 v/v

DISCUSSION

  • Upon addition of HNO3, the evolution of reddish brown (NO2) fumes occurred
  • After 20 minutes, the samples are pale yellow in color and a minor amount of material remains
  • Hydrofluoric Acid can be added for a near total digestion to improve the recoveries of certain elements (see Table 2) for improved Manganese & Magnesium)
  • Boric acid can also be added to re-solubilize any insoluble fluorides and help neutralize any remaining
  • Gold was analyzed by ICP-MS
  • For improved silver and gold recoveries bulk up using a solution of 20% HClv/v

OREAS 990b is a copper-gold-silver concentrate certified reference material (CRM) sourced from the Rosebery metallurgical plant owned and operated by MMG Ltd. The Rosebery mine and plant are located in the north-west region of Tasmania, Australia approximately 300 kilometres north-west of Hobart and 125 kilometres south of Burnie.

Results

Table 1: Results of Reverse Aqua Regia Digestion

Elements

Certified Value

ColdBlock Value 1

ColdBlock Value 2

Average

% RSD

% Recovery

Ag (ppm)

6741

6038

6787

6413

5.8%

95%

Au (ppm)

63.67

63.5

63.1

63.28

0.3%

99%

As (ppm)

7663

7256

7901

7579

4.3%

99%

Ca (ppm)

1650

1664

1578

1621

2.7%

98%

Cd (ppm)

580

558

607

583

4.2%

101%

Cu (wt.%)

16.71

15.3

16.5

15.88

3.9%

95%

Fe (wt.%)

14.45

13.5

14.84

14.17

4.7%

95%

Mg (ppm)

1240

748

730

739

1.2%

60%

Mn (ppm)

2280

1874

1974

1924

2.6%

84%

Pb (wt.%)

8.45

8.11

8.6

8.36

2.9%

99%

S (wt.%)

29.11

26.86

27.1

26.98

0.4%

93%

Sb (wt.%)

1.89

1.73

1.84

1.79

3%

94%

Zn (wt.%)

19.97

18.63

20.46

19.55

5%

98%

Table 2 – Results of Reverse Aqua Regia + HF Direction – Showing Improved Recoveries of Manganese and Magnesium

Elements

Certified Value

ColdBlock Value 1

ColdBlock Value 2

Average

% RSD

% Recovery

Mg (ppm)

1240

1084

1274

1179

8.1%

95%

Mn (ppm)

2280

2097

2156

2127

1.4%

93%

Click here to download the Application Note in PDF format.

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ColdBlock Technologies Inc.
4551 Zimmerman Ave
Niagara Falls, ON L2E 3M5
info@coldblock.ca.