Circular No. 04/2015/TT-BTNMT provides detailed regulations on exploration and classification of reserves, allocation of lead-zinc mineral resources.

CIRCULAR

Regulations on exploration and classification of reserves, resource grading

lead-zinc minerals

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, issued by the Government detailing the implementation of certain 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's Office, the Department of Legal Affairs;

The Minister of Natural Resources and Environment promulgates this Circular regulating exploration and classification of reserves, resource grading for lead-zinc minerals;

PART I
GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular regulates exploration; classification of reserves, resource grading in the exploration of lead-zinc minerals.

Article 2. Applicability

This Circular applies to state management agencies for minerals; organizations engaged in mineral exploration; 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. Lead-zinc 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; 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.

3. Predicted resource group is classified into two levels, including: Level 334a resources and Level 334b resources.

4. Detailed classification tables of reserves and resource grading are specified in Appendix 1 attached to this Circular.

Article 4. Requirements for evaluating Level 121 reserves

d) Hydrogeological conditions, engineering geology conditions, mining conditions, and other relevant natural factors are evaluated in detail to provide reliable data for establishing a mine development project;

a) Determining the shape, size, position, morphological variation rules, and internal structure of lead-zinc ore bodies; delineating detailed boundaries of interbedded layers, lenses without ore or ore not meeting criteria within the ore body and the presence of fractures causing ore displacement;

b) Determining natural ore types, industrial ore grades with distinct characteristics regarding mineral composition, chemistry, structure, architecture, mechanical and technological properties of the ore;

c) Determining the material composition, mechanical and technological properties of various ores; having determined a reasonable beneficiation and separation flow sheet to recover lead-zinc, ensuring sufficient reliable data to determine the ore processing technology flow sheet;

d) Determining geological hydrogeological conditions, engineering geology conditions, mining conditions, and other natural factors related, ensuring sufficient reliable data and parameters to prepare investment projects for mineral exploitation and mine design;

đ) The reliability of reserves must be at least 80%;

2. Boundaries for delineating reserves:

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

3. Assessment of technical feasibility and economic efficiency:

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 evaluating Level 122 reserves

1. Geological assessment level:

a) Determining basic parameters regarding the shape, size, position, morphological variation rules, internal structure, and thickness variation of lead-zinc ore bodies. The number and size of interbedded layers, lenses without meeting reserve calculation criteria inside the ore body.

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

c) Lead-zinc ore quality is assessed in detail, clearly determining the material composition, mechanical and technological properties of various ores; determining a reasonable beneficiation and separation flow sheet;

d) Determining geological hydrogeological features, engineering geology features, 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 of exploration works. For ore bodies with non-complex structures, relatively stable thickness and quality, limited extrapolation according to geological and geophysical data is allowed but not exceeding half of the prescribed grid.

3. Technical feasibility and economic efficiency assessment is carried out in accordance with Clause 3 of Article 4 of this Circular.

Article 6. Requirements for assessing resource level 221

1. The degree of geological assessment and delineation of resource boundaries shall be carried out in accordance with Clause 1 and 2 of Article 4 of this Circular;

2. The assessment of technical feasibility, technology, and economic efficiency shall be conducted in accordance with Clause 3 of Article 4 of this Circular. Resource level 221 refers to 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 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 Clause 1 and 2 of Article 5 of this Circular.

2. The requirements for assessing technical feasibility, technology, and economic efficiency shall be conducted in accordance with Clause 3 of Article 4 of this Circular. Resource level 222 refers to 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. Requirements for geological assessment

a) Basic characteristics regarding the shape, position, and distribution of lead-zinc ore bodies must be determined;

b) The thickness, structure, and stability of lead-zinc ore bodies must be preliminarily determined;

c) The quality of lead-zinc ore must be preliminarily assessed based on samples taken from natural exposures, cleaned sites, trenches, shafts, drilling, or extrapolated from adjacent areas 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;

e) The boundary of resource level 333 should connect along geological structures favorable for the formation of lead-zinc ore bodies, based on the synthesis of geophysical and geochemical research results combined with individual excavation works. Resource level 333 mainly involves extrapolation or within the control range of exploration works that have not yet achieved the network density required for reserve level 122. For small ore bodies, the boundary of resource level 333 must have at least two control works to determine thickness and content.

2. Requirements for assessing technical feasibility, technology, and economic efficiency:

It has not been determined whether exploiting and processing lead-zinc ore from this resource will be economically viable or potentially profitable at the time of assessment.

Chapter III
CLASSIFICATION OF MINES AND REQUIREMENTS FOR EXPLORATION

Article 9. Classification of exploration mine groups

1. Basis for classifying exploration mine groups:

a) Based on the shape, size, position of lead-zinc ore bodies, their stability in terms of thickness, variation in lead-zinc content, and complexity of geological structure;

b) Based on quantitative indicators to assess variations in thickness and content of ore bodies and mining geological conditions to classify exploration mine groups;

c) Based on specific arguments and evaluations of major lead-zinc ore bodies, which account 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 the following 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 classification of exploration mine groups:

a) Simple Mine Group (I):

Includes large mines or parts of large mines with simple geological structures, with ore bodies resembling false beds, horizontal or gently inclined seams; ore bodies have simple shapes, with ore factor from 0.8 to 1.0; stable thickness, thickness variation coefficient according to works not exceeding 40%; main beneficial components' content distributed evenly, content variation coefficient according to single samples not exceeding 40%.

b) Relatively Complex Mine Group (II):

Includes large to medium-sized mines or parts thereof with relatively complex geological structures, with ore bodies having shapes ranging from relatively simple to complex; seam, lens, column, pipe-shaped ore bodies; relatively stable to unstable thickness, thickness variation coefficient according to works from over 40% to 70%; main beneficial components' content distributed from relatively evenly to unevenly, content variation coefficient according to single samples from over 40% to 70%, and ore factor from 0.7 to 0.8.

c) Complex Mine Group (III):

Includes small to medium-sized mines or parts thereof with complex geological structures, with seam, lens, pocket, column, pipe-shaped ore bodies; very complex ore body shapes, unstable thickness, thickness variation coefficient according to works from over 70% to 100%; main beneficial and harmful components' content distributed unevenly, content variation coefficient according to single samples from over 70% to 100%; ore factor from 0.6 to 0.7.

d) Very Complex Mine Group (IV):

Includes small mines or parts thereof with very complex geological structures, with small to very small sized ore bodies, vein, lens, column, pocket-shaped; extremely complex ore body shapes, very unstable thickness, thickness variation coefficient according to works over 100%; main beneficial components' content varies extremely unevenly, content variation coefficient according to single samples over 100%; ore factor below 0.6.

Article 10. General requirements for exploration work

1. Exploration from general to detailed, from surface to deep underground, exploration networks from sparse to dense, geological mapping from small scale to large scale maps;

2. Collecting comprehensive information, data, geological materials, hydrogeological, engineering geological, environmental geological; mining exploitation conditions serving the evaluation, investment project development, 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. Carry out exploration work throughout the entire area and depth where the ore body exists within the boundaries selected in the exploration project.

Article 11. Requirements for topographic basis and geodetic work

1. The area for exploration 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 1/2000 to 1/500, depending on geological structure, ore body scale, and terrain complexity.

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

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

Article 12. Requirements for geological mapping

1. Geological mapping work during lead-zinc exploration shall be carried out at a scale of 1/2000 to 1/1000, depending on the size of the ore body and the complexity of the geological structure of the mine.

2. The geological map must clarify the characteristics of the mine's geological structure, the distribution features of magmatic formations, sedimentary rocks, folds, tectonic fractures, metamorphic zones, mineralization zones, and lead-zinc ore bodies in the mine; it must provide a basis for evaluating the distribution features, formation conditions of the ore, the relationship between the ore body and the surrounding rock, and major geological structures.

Article 13. Requirements for selection and layout of exploration works

1. Selection of exploration works:

a) In lead-zinc ore exploration, various types of excavation works (trenches, shafts, adits) and drilling can be selected. The chosen exploration works must be suitable for the lying position, depth distribution, geological structure, shape, 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 position, shape, internal structure of the ore body, vertical adits or crosscuts should be used, and the use of drilling works should be minimized;

d) Drilling works must recover the highest core samples intact. The sampling rate of core drilling must not be less than 70% through rock and 85% through ore per drill run. To enhance the reliability of drilling works, well logging physical methods must be employed;

đ) For vertical and inclined drill holes deeper than 100 meters, deviation measurements must be conducted every 10 to 20 meters;

e) For ore bodies with large dip angles, inclined or horizontal drilling methods must be applied;

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

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

a) The arrangement of exploration works must ensure a comprehensive evaluation of the characteristics of the geological structure, shape, size, lying position, thickness stability, and quality of the ore body;

b) The exploration work network specified in Appendix 2 issued together with this Circular;

c) All exploration works, mining works, natural and artificial exposures within the exploration area must be promptly, fully, and accurately described, mapped, and documented according to current regulations on collecting original data in mineral exploration and must be plotted on the actual data map;

Article 14. Requirements for sample work

1. Exploration works encountering ore must take detailed and systematic samples to delineate the ore body and assess the quality of the ore regarding its main components. The sampling positions must be clearly indicated on the original documentation.

2. The size of each type of sample must be based on the distribution characteristics of the material components inside the ore body, ensuring the highest reliability and a full assessment of the main components.

3. Principles of sampling:

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

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

c) 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, the main ore body in the mine;

d) Large bulk samples must be taken in a minimum of three samples for each type of natural ore. Along with each large bulk sample, a minimum of three small bulk samples and moisture samples must be taken for analysis and comparison. The volume of large bulk samples ranges from 0.5 to 1 cubic meter;³For hard or thin ore bodies where large bulk samples cannot be obtained, the bulk density of the ore is mainly determined by the average value of small bulk samples. Moisture content of the ore must also be determined alongside the bulk density.

Article 15. Requirements for Sample Processing Work

1. All samples must be crushed and ground to a particle size smaller than 01mm. Further processing and reduction shall be carried out according to the processing scheme for each mine.

2. The quality of sample processing must be systematically checked at all stages, ensuring compliance with the sample processing scheme. All basic analytical samples must be processed to a particle size of 0.074mm before analysis.

Article 16. Requirements for Sample Analysis Work

1. The results of sample analysis must determine the content and form of existence of the main valuable components and accompanying valuable components (if any).

a) The content of lead and zinc must be determined through chemical analysis or other methods, following the current regulations.

b) Basic chemical analysis samples must analyze two components: Pb and Zn. Basic chemical analysis must be conducted on 100% of the samples taken from the exploration site. Harmful components and other components must be identified through group chemical samples, at least 10% of the basic samples.

c) Group chemical samples must represent natural ore types or industrial ore grades. For group samples, in addition to Pb and Zn, additional components such as Cu, S, As, Fe, Au, Ag, Te, and Cd must also be analyzed.

d) The mineral composition, structural and architectural characteristics, and other physical properties of the ore must be evaluated 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 ores, difficult-to-treat ores, or ores without industrial production experience, separate evaluation programs must be established.

The results of technological sample research must assess the material composition of the ore, determine the key economic and technical parameters of the beneficiation stages, and propose reasonable grinding and beneficiation technology schemes to recover the main components.

Article 17. Requirements for Sample Analysis Quality Control Work

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

2. Quality control of sample analysis results must comply with 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 Sample Analysis 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 water-bearing layers, it is necessary to determine their thickness, lithological composition, water supply conditions, and the relationship between water-bearing layers, surface water, groundwater, and related parameters.

d) It is required to study the chemical and microbiological composition of water, assess its corrosiveness to concrete and metals, the content of valuable and harmful components in water, and the impact of mine drainage pumping on underground water usage facilities in the region, as well as the suitability of water for domestic use. Recommend solutions related to water supply and drainage, and the impact of mine drying on the surrounding environment.

2. Requirements for Engineering Geology Evaluation:

a) Exploration results must determine the mechanical and physical properties of the ore, surrounding rock, and overburden under natural and saturated water conditions; the engineering geological characteristics of strata, their anisotropic nature, rock composition, fracturing, tectonic destruction, karst phenomena, and weathering zone destruction.

b) Exploration results must evaluate the stability of mine structures and calculate the basic parameters of the open-pit mining face and shaft stability.

c) All hydrogeological, engineering geological conditions, and other natural factors must be assessed to meet the requirements for investment project development and mine design. In cases where hydrogeological and engineering geological conditions are extremely complex, specialized investigation and evaluation projects must be established. Hydrogeological and engineering geological assessment work must comply with current regulations.

Article 19. Requirements for assessing the level of pollution and environmental impact

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

2. Assess geological disasters, negative impacts on the environment caused by exploration activities, and propose preventive and mitigating measures. The content and extent of the environmental impact assessment must be included in the exploration project proposal.

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 seam face, the slope angle of the pit edge, stripping ratio, volume of overburden, and preliminarily assess the rock pressure on the wall, pillar, and ore body.

2. Evaluate areas without industrial lead-zinc ore 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 lead-zinc ores must be based on detailed reserve calculation criteria set forth in the mineral exploration report for each mine.

2. The method of calculating reserves and resources of lead-zinc ores must be selected appropriately according to the structural characteristics of the ore body for each mine. It is encouraged to apply specialized software for reserve calculations.

3. Reserves and resources of lead-zinc ores are calculated as existing underground reserves, not including losses during extraction and processing, and are expressed in units of thousands of tons for raw ore and tons for lead-zinc metals.

4. Reserves and resources of lead-zinc ores are presented on a reserve calculation map at a scale of 1/2000 to 1/1000, depending on the scale and characteristics of the ore body. Reserve calculation results must be shown separately for each ore body, by reserve grade, resource grade, and up to a maximum height of 10 meters.

Article 22. Requirements for the highest reserve grade and the proportion of reserve grades

1. For mines in Group I and II, the highest reserve category must be Category 121; for mines in Group III and IV, it must be Category 122.

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

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 in accordance with Circular No. 16/2012/TT-BTNMT dated November 29, 2012, issued by the Minister of Natural Resources and Environment regarding the exploration project proposal, closure of mineral mines, and sample reports on mineral activity results, sample documents in the mineral activity permit application file, reserve approval file, and mine closure file.

Chapter IV
IMPLEMENTATION

Article 24. Effective Date

This Circular takes effect from April 1, 2015;

Article 25. Implementation organization

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

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