Circular No. 06/2011/TT-BTNMT on quality control of geological sample analysis results and mineral exploration

CIRCULAR

Regulations on quality control of geological sample analysis results and mineral analysis results

analysis of geological and mineral samples

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MINISTER OF NATURAL RESOURCES AND ENVIRONMENT

Based on the Minerals Law and the Law Amending and Supplementing Certain Provisions of the Minerals Law;

Pursuant to Decree No. 25/2008/NĐ-CP dated March 4, 2008 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

Based on Decree No. 89/2010/NĐ-CP dated September 18, 2010 of the Government amending and supplementing Article 3 of Decree No. 25/2008/NĐ-CP dated March 4, 2008 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

Considering the proposal of the Director of the Vietnam Geological and Mineral Resources Department and the Head of the Legal Department,

c) Enterprises may be granted permission for no more than one block out of the total three dual-frequency blocks (FDD) B

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation and Applicability

1. This Circular prescribes the procedures for quality control and assessment of the reliability of quantitative analytical results of geological samples and mineral samples.

2. This Circular applies to state agencies, laboratories, organizations, and individuals when performing basic geological surveys and basic geological surveys on mineral resources; mineral exploration activities under the management of the Ministry of Natural Resources and Environment.

Article 2. Interpretation of Terms

1Basic Sample is a processed sample taken from a representative portion for analysis according to the requirements of the sender.

2Analytical Retention Sample is the remaining portion with physical characteristics and material composition identical to that of the basic sample and is stored and preserved in accordance with current regulations.

3Quality Control Samples include:

a) Standard Sample is a sample manufactured from soil, rock, or ore officially announced by an authorized agency, accompanied by a certificate.

b) Blank Sample is a sample known to contain less than the detection limit of the analytical method.

c) Duplicate Sample is a sample taken from the processed sample by the sender, coded, and sent together with the basic sample, with the same analytical requirements as the basic sample.

d) Repeated Sample is a sample taken from the analytical retention sample and reanalyzed.

đ) Comparative Sample is a sample taken from the analytical retention sample, coded, and analyzed using a different analytical method or laboratory.

Article 3. Requirements for Quality Control of Analytical Results

1. Quality control of analytical results must be conducted independently from the internal checks organized by laboratories.

2. Quality control must be continuously performed for each batch of samples submitted for analysis. Each batch of basic samples must be accompanied by at least one type of quality control sample. Each batch of basic samples shall not exceed 30 samples.

3. For each analytical index to determine high-grade resources, two to three out of the six types of quality control samples specified in Article 2 of this Circular must be included.

4. The laboratory (or method) used for comparative analysis must have a higher or equal level of reliability compared to the laboratory (or method) used for basic sample analysis.

5. Comparative samples shall be used in cases where there are no suitable standard samples available.

PART II

SELECTION AND SUBMISSION OF QUALITY CONTROL SAMPLES

Article 4. Selection of Quality Control Samples

1. The number of quality control samples depends on the complexity of the object to be analyzed, the capability of the analytical method, and the number of basic analytical samples. The total number of quality control samples must be greater than or equal to 10% of the total number of basic samples.

2. Quality control of analytical results should prioritize areas where high-grade resources are determined.

Article 5. Submission of Samples

1. When submitting quality control samples, all types of samples must be processed to meet the requirements for analysis according to current technical standards and sample processing procedures for geological and mineral analysis.

2. Quality control samples must be coded to ensure scientific accuracy, avoid confusion, and maintain confidentiality for the laboratory.

3. A duplicate sample must be included in the batch of comparative analysis samples in accordance with Clause 2, Article 3 of this Circular.

Chapter III

EVALUATION OF ERRORS AND HANDLING OF ANALYSIS RESULTS

Article 6. Relative Error Evaluation

1. The formula for calculating relative error is used to calculate for basic sample pairs and duplicate samples (or repeated samples or paired samples).

Average value:

Where:

S is the relative error.

 X_Cb is the result of analyzing the basic sample.

X_ks is the result of analyzing the duplicate sample or repeated sample or paired sample.

2. Compare the value of S obtained with the permissible standard deviation δp at the corresponding level of concentration as specified in Appendix 1. The permissible relative error is issued together with this Circular.

If |S| ≤ δp : The analysis result is accepted

If |S| > δp : The analysis result is not accepted.

Article 7. Analysis Sample Standard Error Evaluation

The accuracy for each analytical index is calculated according to the formula: σ = 0.02

With CC being the known value (elemental content or component of the standard sample).

Use the value of Z calculated according to the formula stipulated in Clause 2 of this Article to evaluate the error.

2. Calculate the value of Z :

σ is the accuracy calculated according to the formula.

C_PT: Is the result of analyzing the standard sample.

3. Evaluate the error:

a) If the absolute value of Z is less than or equal to 4 (|Z| ≤ 4), the quality of the analysis is considered good and the analysis results are reliable.

b) If the absolute value of Z is greater than 4 (|Z| > 4), the quality of the analysis is not sufficiently reliable.

Article 8. Paired Sample Analysis Error Evaluation

1. Evaluate the relative error of the paired duplicate sample analysis according to the provisions of Article 6 of this Circular.

a) If the basic analysis result of the paired sample is not accepted, then that analysis result is not used to evaluate the paired error;

b) If the basic analysis result of the paired sample is accepted, that result is used to evaluate the paired analysis error.

2. The paired analysis error evaluation is carried out according to the provisions of Article 6 of this Circular.

a) If the analysis result is accepted, the quality of the basic sample analysis meets the requirements.

b) If the analysis result is not accepted, the quality of the basic sample analysis is not sufficiently reliable.

Article 9. White Sample Analysis Error Evaluation

2.4.1. If the analysis result of the blank sample is lower than the method detection limit, the basic analysis result is considered reliable.

1) If the white sample analysis result is smaller than the method's determination limit, the basic analysis result is sufficiently reliable.

2) If the white sample analysis result is larger than or equal to the method's determination limit, the analysis result is not sufficiently reliable.

Article 10. Handling Analytical Results

1. Prepare a statistical table of analysis results according to the model 1, Appendix II issued together with this Circular.

2. Evaluate errors according to the provisions of Articles 6, 7, 8, and Article 9 of this Circular.

3. Handle errors, compare cases occurring according to the provisions of the Table of Handling Analytical Results as follows.

Table 1: Handling Analytical Results

a) Case 1: The analysis result is sufficiently reliable for use.

b) Case 2: Susceptible to systematic error, the sample sender must notify the laboratory in writing, prepare a record to cancel all analyzed results.

c) Case 3: Susceptible to random error, the sample sender notifies the laboratory in writing for both parties to review, find the cause.

- If the cause of the error is due to the sample sender, they must prepare a record to cancel all analysis results; the sample sender must prepare a new batch of samples according to Clause 2, Article 3 of this Circular for analysis.

- If the cause of the error is due to the laboratory, they must prepare a record to cancel all analysis results, the laboratory is responsible for re-analyzing the sent batch of samples.

d) Case 4: The analysis result is not sufficiently reliable for use, the sample sender must notify the laboratory in writing, prepare a record to cancel all analysis results; stop sending samples to the laboratory, report to the management authority for consideration and resolution.

Chapter IV

RESPONSIBILITIES OF THE ORGANIZATION AND INDIVIDUAL SAMPLE SENDERS AND LABORATORY

Article 11. Responsibilities of organizations and individuals sending samples

1. Quality control work for sample analysis is a mandatory requirement when carrying out basic investigation tasks on ore and basic investigation tasks on mineral resources; mineral exploration.

2. In the report on the results of implementation, all quality control data must be fully compiled, and the reliability of the analytical results used in the report must be evaluated. The basic content of the quality control work report is stipulated in Appendix 2 issued together with this Circular.

3. Within thirty days from receiving the analysis results, the party sending the sample must process and evaluate the quality of the quality control sample analysis. If any type of quality control sample does not meet the requirements, the party sending the sample must notify the laboratory in writing to jointly examine, investigate the cause of errors, and agree on measures to handle them. The record shall be made according to the provisions in Appendix 2 issued together with this Circular. If the cause of error is due to the party sending the sample (such as sample mix-up, incorrect sample coding, unsuitable sample selection...), when re-analyzing, the party sending the sample must bear the costs.

4. All records shall be kept in the original file.

Article 12. Responsibilities of the laboratory

1. Create favorable conditions for the party sending the sample to take duplicate samples, repeat samples, and paired comparison samples for storage and analysis.

2. When receiving feedback from the party sending the sample, the laboratory must provide a written response regarding the quality of the sample analysis within ten days.

3. If the cause of error is due to the laboratory, when re-analyzing, the laboratory must bear the costs.

CHAPTER V

IMPLEMENTING PROVISIONS

Article 13. Budget for implementing quality control work

In projects for basic ore investigations and basic investigations on mineral resource ore, and mineral exploration, the number of samples sufficient for quality control must be designed. The budget for implementing quality control methods is included in the project cost estimate.

Article 14. Effective Date

1. This Circular takes effect from March 15, 2011. Decree No. 69/QĐ-ĐC/KT dated May 29, 1996 of the Director of the Vietnam Geological Survey on regulations for checking the content of elements in ore samples is abolished.

2. The Director of the Vietnam Geological Survey and Mineral Resources, subordinate units under the Ministry of Natural Resources and Environment, organizations and individuals implementing projects, laboratories are responsible for enforcing this Circular.