Circular No. 03/2015/TT-BTNMT on exploration and classification of reserves and allocation of primary gold mineral resources

CIRCULAR

Regulations on exploration and classification of reserves, on primary gold mineral resources

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Pursuant to the Minerals Law No. 60/2010/QH12 dated November 17, 2010;

Pursuant to Decree No. 15/2012/NĐ-CP dated March 9, 2012 of the Government detailing some provisions of the Minerals Law;

Pursuant to Decree No. 21/2013/NĐ-CP dated March 4, 2013, promulgated by the Government, stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

At the proposal of the Director of the National Mineral Reserve Evaluation Council Office and the Director of the Legal Department;

The Minister of Natural Resources and Environment issues this Circular stipulating exploration and classification of reserves, allocation of primary gold mineral resources.

PART I
GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates exploration and classification of reserves, allocation of mineral resources in the exploration of primary gold mineral resources.

Article 2. Applicability

This Circular applies to state management agencies for minerals; organizations engaged in mineral exploration activities; organizations and individuals involved in mineral exploration and exploitation, and other organizations and individuals related to mineral activities.

Chapter II
b) Predicted resources.

Article 3. Classification of reserves and resource grading

1. Primary gold mineral resources are divided into two groups:

b) The resource type is classified into three levels, including level 221; level 222 and level 333.

3. The predicted resource group is classified into two levels, including level 334a and level 334b.

4. The classification table of reserves and resources of copper minerals is specified in Appendix 1 attached to this Circular.

a) Reserves are classified into three levels, including Level 111 reserves, Level 121 reserves, and Level 122 reserves.

b) Resources are classified into six levels, including Level 211 resources; Level 221 resources; Level 222 resources; Level 331 resources; Level 332 resources, and Level 333 resources.

a) Determination of the ore deposit structure; characteristics of shape, size, position, variation patterns of shape and internal structure of the ore body; detailed delineation of boundaries of interbedded rock layers and lenses without ore according to reserve calculation criteria, presence of faults causing ore displacement;

4. The detailed classification table of reserves and resource levels is specified in Appendix 1 attached hereto.

Article 4. Requirements for evaluating Level 121 reserves

1. Geological assessment level:

a) Determining the shape, size, position, pattern of morphological changes, internal structure, and boundaries of interbedded rock layers, lenses without ore or with ore not meeting standards, and the presence of faults causing ore displacement;

b) Identifying natural ore types and industrial ore grades with distinct characteristics regarding mineral composition, structure, architecture, chemical composition, physical-mechanical properties, and technological properties of ores;

c) Determining the material composition, physical-mechanical properties, and technological properties of various ore types; establishing a reasonable ore processing flow sheet and leaching process for gold recovery, ensuring sufficient reliable data to determine the ore processing technology flow sheet;

d) Determining geological hydrogeological conditions, engineering geology conditions, mining conditions, and other relevant natural factors in detail, providing sufficient reliable data to prepare investment projects for mineral exploitation and mine design;

a) Reasonable ore processing technologies have been selected based on technological sample research results or investment construction project reports;

2. Boundaries for delineating reserves:

The boundary of Level 121 reserves is delineated within the control range defined by exploration works and/or mining works.

3. Technical and economic feasibility assessment:

a) Selecting reasonable technical and technological solutions for ore extraction and processing;

b) The reserve level is economically viable based on reserve calculation criteria.

Article 5. Requirements for assessing Level 122 reserves

1. Geological assessment level:

a) Determining basic parameters regarding the shape, size, position, pattern of morphological changes, internal structure, and thickness variation of primary gold ore bodies. The number and size of interbedded rock layers not meeting reserve calculation criteria inside the ore body;

b) Distinguishing natural ore types and industrial ore grades based on mineral composition, structure, architecture, chemical composition, physical-mechanical properties, and technological properties of ores;

c) Detailed evaluation of the quality of primary gold ore, determining the material composition, physical-mechanical properties, and technological properties of various ore types; establishing a reasonable ore dressing and gold leaching process;

d) Determining geological hydrogeological features, engineering geology conditions, and mining technical conditions as a basis for preparing investment projects for mineral exploitation and mine design;

đ) Reliability of the minimum assured reserve of 50%.

2. Boundaries for delineating reserves:

The boundary of Level 122 reserves is delineated within the control range defined by exploration works. For ore bodies with non-complex structures, stable thickness and quality, limited extrapolation based on geological and geophysical data is allowed but must not exceed half of the prescribed grid spacing.

3. Technical, technological feasibility and economic efficiency assessment shall be carried out in accordance with Clause 3 of Article 4 of this Circular.

Article 6. Requirements for assessing resource level 221

1. Geological assessment level and delineation of resource boundaries shall be conducted in accordance with Clauses 1 and 2 of Article 4 of this Circular.

2. Technical, technological feasibility and economic efficiency assessment shall be carried out in accordance with Clause 3 of Article 4 of this Circular. Level 221 resources refer to resources that have been explored but do not meet reserve calculation criteria or are located in areas prohibited or temporarily prohibited from mineral activities.

Article 7. Requirements for assessing resource level 222

1. The requirements for geological assessment and delineation of resource level 222 boundaries shall be carried out in accordance with the provisions of Clause 1 and Clause 2 of Article 5 of this Circular.

2. The requirements for technical feasibility, technological assessment, and economic efficiency shall be implemented according to Clause 3 of Article 4 of this Circular. Resource level 222 is part of the resources that have been explored but do not meet the criteria for reserve calculation or are located in areas prohibited or temporarily prohibited from mineral activities.

Article 8. Requirements for assessing resource level 333

1. Geological assessment requirements:

a) Determine the basic characteristics regarding the shape, position, and distribution of primary gold ore bodies;

b) Preliminarily determine the thickness, structure, and stability of primary gold ore bodies;

c) The quality of primary gold ore is preliminarily determined based on sampling results from natural exposures, cleaning works, trenches, shafts, drilling, or extrapolation using data from adjacent sections with more detailed geological assessments;

d) Natural factors determining mining conditions do not need to be detailed evaluated at this stage, mainly understood and compared with nearby areas that have undergone more detailed assessments;

d) The boundary of resource level 333 is delineated based on geological structural boundaries favorable for the formation of gold ores, synthesized from geophysical and geochemical evaluation results combined with individual mining works. Resource level 333 mainly consists of extrapolations or within the control range of exploration works that have not reached the 122 grade reserves; for small ore bodies, the boundary of resource level 333 must have at least two control works determining the thickness and identifying the content.

2. Technical feasibility, technological assessment, and economic efficiency evaluation:

It has not yet been determined whether the exploitation and processing of gold ores from this resource source will be economically viable or potentially economically viable at the time of assessment.

Chapter III
CLASSIFICATION OF MINES AND REQUIREMENTS FOR EXPLORATION TECHNIQUES

Article 9. Classification of exploration mine groups

1. Basis for classifying exploration mine groups:

a) Based on the shape, size, position of primary gold ore bodies, the stability of thickness, variation in gold content, and the complexity of the mine's geological structure;

b) Based on quantitative indicators for evaluating the variation in thickness, gold content, and mining geological conditions to classify exploration mine groups;

c) Based on specific arguments and evaluations of the main primary gold ore body, which accounts for no less than 70% of the mine's reserves. Exploration mine groups are proposed in the Mineral Exploration Plan and confirmed in the Mineral Exploration Results Report.

2. Classification of exploration mine groups into categories:

a) Simple Mine Group (I);

b) Relatively Complex Mine Group (II);

c) Complex Mine Group (III);

d) Very Complex Mine Group (IV).

3. Conditions for classifying exploration mines

a) Simple Mine Group (I):

Includes mines or parts of mines with simple geological structures featuring large vein or lens-shaped ore bodies lying horizontally or gently inclined, with simple shapes; stable ore body thickness, thickness variation coefficient along exploration works not exceeding 40%; even distribution of major valuable components, variation coefficient along single samples not exceeding 40%, and ore grade factor from 0.8 to 1.0;

b) Relatively Complex Mine Group (II):

Includes medium to large mines with relatively complex geological structures featuring large vein or lens-shaped ore bodies; relatively stable to unstable ore body thickness, thickness variation coefficient along exploration works from over 40% to 100%; uneven to relatively even distribution of major valuable components in ore bodies, variation coefficient along single samples from over 40% to 100%, and ore grade factor from 0.7 to 0.8;

c) Complex Mine Group (III):

Includes small to medium mines with complex geological structures featuring bedded, vein, lens, pod, column, pipe-shaped ore bodies; complex ore body shapes, unstable ore body thickness, thickness variation coefficient along exploration works from over 100% to 150%; uneven distribution of major valuable components, variation coefficient along single samples from over 100% to 150%, and ore grade factor from 0.6 to 0.7;

d) Very Complex Mine Group (IV):

Includes small mines with very complex geological structures featuring small to very small vein, network, lens, column, pod-shaped ore bodies; extremely complex ore body shapes, particularly unstable ore body thickness, thickness variation coefficient along exploration works over 150%; extremely uneven distribution of major valuable components, variation coefficient along single samples over 150%, and ore grade factor below 0.6.

Article 10. General requirements for exploration work

1. Exploration from general to detailed, from surface to deep, exploration grid from sparse to dense, geological mapping from small scale to large scale.

2. Collecting comprehensive information, data, geological, hydrogeological, engineering geological, environmental geological, and mining conditions to serve the preparation of investment projects for mineral exploitation and mine design.

3. The exploration sequence is established based on compatibility with the complexity of geological structure, reserve scale, and economic value of the mine.

4. Conduct exploration work throughout the entire area and depth of the ore body within the selected exploration project boundary.

Article 11. Requirements for topographic basis and geodetic work

1. The exploration area must carry out topographic survey work at corresponding scales as required by the exploration work. Topographic maps must be established according to current regulations on geodetic work in mineral exploration. The scale of topographic maps ranges from 1/2,000 to 1/500, depending on the geological structure and ore body size.

2. Exploration works and corner points in the exploration area must determine coordinates, elevations, and relationships with the national coordinate network according to current regulations on geodetic and geological work.

3. The exploration area must use at least two national boundary markers.

Article 12. Requirements for geological mapping

1. Geological mapping during primary gold ore exploration is conducted at scales ranging from 1/2,000 to 1/1,000, depending on the size of the ore body and the complexity of the mine's geological structure.

2. Geological maps must clearly depict the characteristics of the mine's geological structure, the distribution features of magmatic formations, sedimentary formations, folds, fault zones, tectonic zones, metamorphic zones, mineralization zones, primary gold ore bodies in the mine; providing a basis for evaluating the distribution characteristics, ore-forming conditions, ore-mineral associations with surrounding rocks, and the main geological structure.

Article 13. Requirements for selection and layout of exploration works

1. Selection of exploration works:

a) In primary gold ore exploration, excavation works (trenches, shafts, adits) and drilling can be selected. The chosen exploration works must be suitable for the position, depth distribution, geological structure, morphology, thickness of each ore body, and the characteristics of the overburden layer.

b) At each work site, detailed samples must be taken to determine the quality, distribution patterns of various types of ore, depth of weathering, structural characteristics of ore body walls and pillars;

c) For mines with very complex geological structures, to clarify the lying conditions, shapes, and internal structures of ore bodies, shaft works along seams or across seams shall be used, and the use of drilling works shall be limited.

d) Drilling works must recover the highest percentage of intact core samples. The sampling rate for core samples should not be less than 70% for each drilling interval through rock and 85% when drilling through ore. To enhance the reliability of drilling works, it is encouraged to use borehole geophysical methods.

đ) For drill holes deeper than 100 meters, deviation and inclination angles must be measured every 10 to 20 meters.

e) For ore bodies with steep inclinations, inclined drilling or horizontal drilling methods should be applied.

g) Exploration works must intersect the entire thickness of the ore body.

2. Arrangement of exploration works and selection of exploration network density:

a) The layout of exploration works must ensure a comprehensive evaluation of the geological structure characteristics, morphology, size, lying conditions, stability in thickness, and quality of ore bodies.

b) The network of exploration works is specified in Appendix 2 issued together with this Circular.

c) Exploration works, mining works, natural and artificial exposures within the exploration area must be described, geologically mapped, and original documentation established promptly, fully, and accurately according to current regulations on collecting original documentation in mineral exploration and plotted on actual documentation maps.

Article 14. Requirements for Sampling Work

1. Detailed and systematic sampling must be conducted at exploration works encountering ore to delineate ore bodies and assess the quality of major components. The sampling locations must be detailed on original documentation.

2. The size of various types of samples must be based on the distribution characteristics of material components inside the ore body, ensuring the highest reliability and a full assessment of major components.

3. Principles of sampling:

a) At works encountering ore, continuous sampling must be conducted to ensure sufficient basis for delineating the boundaries of ore bodies and interbedded layers. The length of channel samples is determined by the internal structure of the ore body; changes in material composition; structural, architectural, and mechanical properties of the ore.

b) The results of sampling for each type must be presented graphically;

c) Technology test samples must represent the chemical composition, mineralogical composition, mechanical properties, particle size, and other properties consistent with the average composition of each type of ore and main ore body in the mine.

d) Large bulk samples must be taken at least three for each type of natural ore. Each large bulk sample must be accompanied by at least three small bulk samples for analysis and comparison. The volume of large bulk samples ranges from 0.5 to 1 cubic meter. For hard or thin ore bodies where large bulk samples cannot be obtained, the bulk density of the ore is determined by the average value of small bulk samples. Along with determining the small bulk density, the moisture content of the ore must also be determined.

Article 15. Requirements for Sample Processing Work

1. All samples must be crushed and ground to a particle size smaller than 1mm, subsequent processing and reduction must follow the processing scheme for each mine.

2. Sample processing quality must be systematically checked at each stage, compliance with the sample processing scheme must be verified.

3. In cases where the ore contains naturally occurring gold that needs washing, gold particles must be recovered before crushing and grinding at sieve sizes of 0.1 mm.

Article 16. Requirements for Sample Analysis Work

1. Analytical results of samples must determine the content and form of existence of the main valuable component and accompanying valuable components (if any).

a) The content of Au and Ag in primary gold ore is determined by fire assay or atomic absorption spectrometry, following current procedures.

b) Basic analytical samples must analyze two components, Au and Ag. Basic analysis is performed on 100% of the samples collected at exploration works. Harmful components and other components are analyzed in group samples, which must be at least 10% of the basic samples.

c) Group samples must represent natural ore blocks or industrial grades of ore. For group samples, in addition to Au and Ag, components such as Cu, As, Pb, Zn, Sb, WO3, S, Hg, Bi, Se, Te must also be analyzed.

d) Mineralogical composition, structural features, grain size of gold, and other physical properties of the ore must be studied using petrographic, mineralogical, physical, chemical, and other analytical methods.

đ) Technological sample research work:

Technological samples must be studied at laboratory scale or expanded laboratory scale. For new types of ores, difficult-to-treat ores, or ores without industrial production experience, specific research programs must be developed.

Technological sample research results must evaluate the ore's material composition, determine key economic and technical parameters for grinding, beneficiation, and gold leaching processes, and propose reasonable technological schemes for recovering gold and silver metals.

Article 17. Requirements for Sample Analysis Quality Control Work

1. Sample analysis inspection must be regularly and systematically conducted.

2. Quality control of analytical sample results is carried out according to Circular No. 62/2014/TT-BTNMT dated December 9, 2014, issued by the Minister of Natural Resources and Environment regarding National Technical Regulations on Quality Control of Geological and Mineral Analytical Results.

Article 18. Requirements for Hydrogeological and Engineering Geological Evaluation

1. Requirements for Hydrogeological Evaluation:

a) Collect hydro-meteorological data of the exploration area for at least the last five years.

b) Exploration results must evaluate the main water-bearing layers that could flood the mine, especially in the most flood-prone parts of the mine to address drainage and mine drying issues.

c) For aquifers, thickness, lithology, water supply conditions must be determined; relationships between aquifers must be identified; relationships between surface water, groundwater levels, and related parameters must be determined.

d) Chemical and microbiological components of water must be studied, the potential for concrete and metal corrosion, the content of valuable and harmful components in water, and the impact of mine dewatering on underground water usage facilities in the region, as well as the suitability of water for domestic use must be assessed. Recommendations for water supply and drainage solutions and the extent of environmental impact due to mine dewatering must be provided.

2. Requirements for Engineering Geology Evaluation:

a) Exploration results must clarify the mechanical properties of ore, surrounding rock, and overburden under natural and water-saturated conditions; geological engineering characteristics of strata, their heterogeneity, rock composition, fracturing, destruction, karst, and weathering phenomena.

b) The survey results must assess the durability of the mine structure and calculate the basic parameters of the mining pit, the stability of the shaft.

c) All geological and hydrogeological conditions, engineering geology conditions, and other natural factors need to be evaluated to meet the requirements for establishing investment projects for mineral exploitation and mine design. In cases where geological and hydrogeological conditions and engineering geology conditions are complex, specialized investigation projects must be carried out. Geological and hydrogeological investigations must comply with current regulations.

Article 19. Requirements for Environmental Impact Assessment

1. The exploration process must collect geological environmental data to forecast and assess the main factors affecting the environment.

2. Assess geological hazards, negative impacts on the environment caused by the exploration of primary gold deposits, and propose preventive and mitigation measures. The content and level of environmental impact assessment must be included in the exploration project.

Article 20. Requirements for technical evaluation work for mine exploitation conditions

1. Preliminarily evaluate the boundaries of the mining area, the slope angle of the ore layer, the slope angle of the pit edge, the stripping ratio, and the volume of overburden; preliminarily assess the rock pressure on the walls and pillars of the ore body.

2. Evaluate areas without industrial gold deposits as the basis for establishing investment projects for mineral exploitation and mine design.

Article 21. Work on calculating reserves and resources

1. Calculating reserves and resources of primary gold deposits must be based on detailed criteria for calculating reserves explained in the report on the results of mineral exploration for each deposit.

2. Methods for calculating reserves and resources of primary gold deposits must be selected in accordance with the structural characteristics of the ore body in each deposit. Specialized software is encouraged for calculating reserves.

3. Reserves and resources of gold deposits are calculated as existing underground reserves, not including losses during extraction and processing, and are expressed in units of thousands of tons for ore reserves and kilograms for gold metal reserves.

4. Reserves and resources of primary gold deposits are shown on reserve calculation maps at scales from 1/2,000 to 1/500, depending on the scale and characteristics of the ore body. Reserve calculation results must be presented by ore body, by reserve grade, and up to a maximum height of 10 meters.

Article 22. Requirements for the highest reserve grade and the ratio between reserve grades

2. The proportions of grades 121 and 122 are determined by the investor based on the geological characteristics of the mine, financial capacity, technical conditions for exploitation, expected production capacity, but must ensure that the proportion of the highest grade reserve to the total reserve of the mine is not less than 10%, and must be reflected in the exploration project proposal.

2. The ratio of reserve grades 121 and 122 shall be determined by the investor based on the geological characteristics of the deposit, financial capacity, technical mining conditions, expected mining capacity, but must ensure that the ratio of the highest reserve grade to the total deposit reserves does not fall below 10%, and must be reflected in the exploration project.

Article 23. Content and Presentation Form of the Mineral Exploration Result Report

The content and format of the report on the results of exploration shall be implemented according to Circular No. 16/2012/TT-BTNMT dated November 29, 2012, issued by the Minister of Natural Resources and Environment regarding the exploration project, closure of mineral deposits, and templates for reporting on mineral activities, sample documents in the permit application dossier for mineral activities, approval dossier for mineral reserves, and closure dossier for mineral deposits.

Chapter IV
IMPLEMENTATION

Article 24. Effective Date

This Circular takes effect from April 1, 2015.

Article 25. Implementation organization

1. The Office of the National Mineral Reserve Evaluation Council, Vietnam General Department of Geology and Minerals shall be responsible for guiding, inspecting, and implementing the provisions of this Circular.

2. During implementation, if there are difficulties or obstacles, organizations and individuals shall promptly reflect them to the Ministry of Natural Resources and Environment for consideration and resolution./.