In a mining context, metal accounting refers to the process of tracking the production and sale of metal products extracted from a mine. This process involves recording the quantities of metal ore that are extracted, processed, and sold, as well as the value of the metal at the time of sale.
“Metal accounting is the estimation of metal in a mine and its process streams over a defined time period. Comparisons of estimates, from different nodes over a specific time period, are known as reconciliation. “
The AMIRA P754 Code for Metal Accounting was established in its current version in 2007, and is the widely accepted best practise standard for metal accounting. For more detail on this standard, read our article, “What is the AMIRA P754 code?”.
Metal accounting is important for a number of reasons, including ensuring that the mine is operating efficiently, accurately reporting production and financial results to stakeholders, and complying with legal and regulatory requirements related to metal production and sales.
Metal mass balance is the process of accounting for the amount of metal that is produced, used, and lost during the process. This is important because it helps to ensure that the metal production process is efficient and that the mining operation is sustainable. To achieve metal mass balance, mining companies typically use a combination of metallurgical accounting and process modeling techniques.
Metal accounting relies on measurements obtained from a network of samples and sensors in the plant. Measurements are typically taken from multiple nodes and include:
Manual logging;
SCADA systems, eg:
platform scales and weighbridges;
conveyor belt weighers, weigh bins or hoppers;
magnetic flow meters and density meters;
spectral analysers;
RFID tags
Sampling and lab analysis associated with materials at various nodes.
Timeous, consistent and robust information collection and analysis requires robust data collection and information management methods. Automated collectors, barcoding of material samples, and integration with LIMS systems, for example, are key to managing and beneficiating so much data.
“Measuring data has a certain amount of statistical error, so when dealing with data it is important to have a good understanding of the errors.”
It's also important to understand two concepts - accuracy and precision. Accuracy is how close the measurement is to an accepted standard. Precision is if the measurements give the same results when repeated - if the results aren't close to what is expected then there is bias. Detecting and managing for bias is difficult without advanced information management and metal accounting systems and calculation engines.
Metal accounting can only take place if a suitable measurement network enables the relevant node reconciliations through the process. The design and implementation of the measurement network, and the handling of data impacts on the precision to which variables of interest, such as the final metal produced, can be estimated and reported on.
Process modeling involves using computer simulations to model the metal production process, including the various stages of mining, processing, and refining. This can be used to optimize the process (for example, using a trained multi-variable solver) and identify opportunities for improving metal recovery and reducing metal losses.
Together, metal accounting and process modeling techniques can help mining companies to achieve metal mass balance and improve the efficiency and sustainability of their operations. Properly designed and implemented metal accounting procedures and reporting functions are a powerful tool to manage a mine’s:
production variability;
unexplained material losses and gains in pay metals;
process inefficiencies;
production forecasting problems.
To this day it is still common for excel spreadsheets to be used to collect, store and process metallurgical accounting data. Daily and month-end reports are generated by time-consuming copying and paste of data into different worksheets or are channelled through dynamic linking to other Excel sheets.
“Spreadsheets propagate errors easily, and cannot guard-rail the integrity of a mine's production data.”
Spreadsheet solutions don’t reliably integrate with third party management systems, and do not deliver the event based reporting or alerting of much more sophisticated IoT solutions. They also lack the auditing and change tracking capabilities of database systems or IoT solutions. Spreadsheet solutions do not satisfy the AMIRA P754 code.
Metal accounting software is used to manage and track the production and sale of metal products extracted from a mine. The software helps to automate and streamline the metal accounting process by providing tools for recording and analysing data related to metal production, such as the quantities of metal ore extracted, processed, and sold, as well as the value of the metal at the time of sale.
A good metal accounting solution will come with:
a consolidated and structured database that integrates mine data collected from multiple sources, including LIMS;
proper SOPs for for metal accounting;
automated, digital data workflows wherever possible;
advanced calculation engines for metallurgical processes and multi-node reconciliation;
multi-variable solvers for process optimisation;
value driver trees for root cause analysis against any tracked parameter;
auditable change logs;
automated reporting and alerting systems; and
A visual, easy-to-interpret dashboards, for that control room experience.
Typically these functions are delivered through cloud solutions and IoT architectures.
“The nascent promise of artificial intelligence (AI) and machine learning has the mining industry abuzz, and AI-led productivity benefits would rely heavily on the data consolidation provided by cloud solutions or local data lakes.”
Reporting is an essential component of the metal accounting function, and management of performance of the operations in focus. Reports should provide information to all levels of operations, from the operators and supervisors controlling the daily plant throughput to the senior management directing the planning and operation of the entire mineral extraction and recovery undertaking. Reports can also facilitate the scheduling of dispatches of product, support efficient settlement and negotiation of long and short-term sales contracts, and provide information efficiently in the preparation of financial accounts for the reporting period concerned.
Mature metal accounting software systems may also include features for managing other aspects of the mining operation, such as inventory management, supply chain management, logistics, settlement and financial reporting, and can integrate with other ERP systems. Pit-to-port integration is the obvious opportunity, breaking down siloed digitalisation. The specific features and capabilities of metal accounting software can vary widely depending on the vendor and the specific needs of the mine.
To learn about Metal Accounting in WIRE, the proprietary pit-to-profit IoT solution for mining from Metal Management Solutions, click here.