One of the main objectives of mining is to make the ore exploited marketable. For this to be possible, strict quality control is required at all stages of the process (exploration, prospecting and mineral research).
However, the use of good practices was not widely required in mining projects until the 1990s. The application of standards and procedures to obtain data reliability was required after the Bre-X project scandal in 1997.
The Bre-X case is considered the biggest fraud in mining history. This event generated a great doubt about the credibility of the classifications of resources and reserves, being the starting point for the consolidation of international conducts.
Some consequences of the Bre-x case:
- Fall in the world stock exchanges on which the shares of mining and exploration companies were traded;
- Drastic reduction of mineral exploration in the world;
- Revision of Mining Codes;
- Preparation of new regulations and recommendations for good practice;
After the event, in order to obtain quality and confidence in the data generated, the mineral industry began to be guided by standards and procedures defined by international standards, such as the JORC code, CRIRSCO, as well as the new CBRR Guide in Brazil.
The establishment of standards for reporting resources and reserves, data from drilling, chemical analysis and geological models, as well as the need for these activities to be validated by competent, qualified and certified professionals in international geoscientific communities, is a requirement that aims to prevent the occurrence of new fraud.
The strategy for obtaining the necessary data for quality assurance and control is known as QAQC and must take into account multidisciplinary contributions that include statistics, geostatistics, geology and the theory of sampling (TOS), which are fundamental to establish goals of precision and accuracy.
Let's talk a little more about it?
In today's text we will address:
- What is QA/QC?
- What is the purpose of QA/QC?
- What are the application areas of QA/QC in mining?
What is QA/QC?
QA/QC defines programs and procedures that meet quality standards in order to identify and, mainly, CORRECT errors in a process. However, there are still certain misunderstandings between these two terms. Therefore, let's understand each of them and then understand their importance in mining.
- Assurance Control (QA). Set of pre-established activities necessary to ensure that a given activity or operation reaches an acceptable degree of quality;
- Quality Control (QC), or quality control. Set of techniques and activities of an operational nature, used to determine the level of quality actually achieved in an operation;
The role of QA/QC in mining is related to the procedures, techniques and tools for sampling work, databases, laboratory tests and any studies related to the exploration of mineral resources and mineral prospecting, ensuring the quality control and security of this information.
These processes must be understood and applied in ALL phases of mineral research and are not limited to the insertion of control tools (blanks, standards and duplicates for chemical analysis). They must be created according to the criteria and needs of each mineral deposit, and it is not feasible for projects of other companies to use previously created procedures.
What is the purpose of QA/QC?
QA/QC aims to ensure reliability in the data generated from the beginning of the project to the mining and operation phase, ensuring that data such as ore grade and amount of mineral reserve are reliable.
The application of QA/QC procedures must occur throughout the mineral survey. It is important to note that only with quality control and assurance is it possible to meet the requirements of the consumer market, providing highly reliable products and services.
The use of sophisticated quality control methods can only be justified if the data on which they are based is precise, accurate and secure. The results are generated based on the confidence of these estimates.
Therefore, this is the importance of QA as a tool that acts from the beginning of the project to prevent errors from being made, and of QC as an active, statistical process that aims to correct, improve processes and take corrective measures.
What are the application areas of QA/QC in mining?
QA/QC can be applied in several stages in mineral research and exploration, in general they are:
QAQC applied to Mineral Research
This phase is the beginning of a mining enterprise in which it is necessary to know the ore, its characteristics, content, resources and reserves and the real feasibility of the project. For this, TRANSPARENCY and RELIABILITY in the data are necessary.
QA can be applied in sampling procedures, description of core cores, density measurements, database preparation and management, etc.
QC can be applied in probe location, control of borehole deviations, sampling, analytical results etc.
QAQC applied to Chemical Analysis
A very important phase in a mineral project, chemical analysis is responsible for determining the ore content found in a research or mining area. Therefore, a reliable and transparent result of the analytes is essential. Some control tools are inserted in the sampling process or used during physical preparation and chemical analysis, each one has its function within the chain.
QA can be applied in the definition of patterns, blanks, duplicates, replicates to be used throughout the entire process of sampling, preparation and analysis.
QC can be applied in the generation of graphs and reports to track the performance of these processes.
Some controls applied are: Mass control (controls the initial mass versus final mass of the process, helps in the identification of exchanged or lost samples), preparation blank (evaluates possible contamination due to poor cleaning of the equipment), duplicates (precision measure), reference materials (standards, accuracy measure, sample with known reference content), check assay (measure reproducibility, Analysis carried out in a secondary laboratory
QAQC applied to the Database
The Database (DB) is the repository of mineral deposit information. If the information contained therein is incorrect, all steps already carried out, as well as future work, may be compromised. In this way, it is expected that all data is properly validated, ensuring decision-making.
It is highly recommended that an administrator be appointed to manage the information in the database and that different permissions be assigned to each type of user, so that the manipulation of the data is completely traceable and auditable.
QA can be applied in defining the format for inserting information, the routines and scripts for validating the information, and also which professionals will be responsible for this insertion.
The QC can be applied to define the frequency that the backup of this information will be performed.
The use of erroneous information such as hole coordinates and under- or overestimated grades can make the mineral project unfeasible.
QAQC applied to Geological Modeling
The geological model is a three-dimensional representation of the mineral deposit, based on sampling data (drilling, channels, trenches, etc.), density and ore content found in a given study area.
QA can be applied when defining what information will be used for model creation.
QC can be applied when performing reconciliation (comparing model estimates to actual production).
Thus, a good QA/QC program is one that is active and is reviewed throughout the data collection, allowing corrective actions to be taken quickly.
In this sense, projects that apply good practices are prepared and organized for internal or external audits. In this way, they improve the productivity of the teams, reduce costs with unnecessary rework and make the project more attractive to investors.
Therefore, the monitoring of the main process indicators through a quality control program (QA/QC) must be constant so that an effective and continuous improvement of the process occurs, preventing the same errors from being repeated in the future.
Therefore, count on Saga to implement quality control procedures in your project. We work with diversified types of warehouses, offering quality services at any level of study. Click here and learn more!
References
- CSA Global.
- Geoscan.
- SRK.
- Igeological.
- IB Mining.
- Minere Institute.
- Mining Technician.
- QAQC GeoAnsata Course Material.
- QAQC Instituto Minere Course Material.