Metal accounting – AMIRA code principles

Metal accounting estimates the quantity of saleable metals produced over a defined period of time (Morrison, 2008a). The AMIRA P754 code of practice for metal accounting defines metal accounting best practices. What metal accounting is all about? What are the challenges? Learn how implement a successful metal accounting system following the AMIRA P754 principles.

What is metal accounting ?

Why implement a metallurgical system?

A metallurgical accounting system is widely used to quantify the performances of production plants and to estimate as accurately as possible the metal inventory. It is designed to:

• Enhance corporate governance and decision making,
• Improve auditability and transparency of metal accounting and reporting process,
• Optimize overall plant efficiency and profitability from mine-to-product,
• Increase performance measurement and minimize risk,
• Improve process control: effluent gas emissions, loss and theft detection…

The starting point of an efficient metal accounting system is a precise understanding of the process operations. It should rely on an accurate sampling and measurement system. It is common to say about metal accounting software that if bad data are sent in the software, inaccurate results will be obtained, often summarized as: “Garbage in, garbage out”.

The 10 metal accounting main principles

In 2005, the AMIRA P754 project established a code of best practice for implementing efficient and reliable metal accounting systems. Metal accounting system must comply with this code. 

The recommendations of the P754 Amira code can be summarized in ten main principles that INVENTEO, CASPEO metallurgical accounting solution, allows or helps to apply.

1. The metal accounting system must be based on accurate measurements of mass and metal content. It must be based on a full Check in-Check out system using the Best Practices as defined in this Code, to produce an on-going metal/commodity balance for the operation. The system must be integrated with management information systems, providing a one-way transfer of information to these systems as required.

2. The system must be consistent and transparent and the source of all input data to the system must be clear and understood by all users of the system. The design and specification of the system must incorporate the outcomes of a risk assessment of all aspects of the metal accounting process.

3. The accounting procedures must be well documented and user friendly for easy application by plant personnel, to avoid the system becoming dependent on one person, and must incorporate clear controls and audit trails. Calculation procedures must be in line with the requirements set out in this Code and consistent at all times with clear rules for handling the data.

4. The system must be subject to regular internal and external audits and reviews as specified in the relevant sections of the Code to ensure compliance with all aspects of the defined procedures. These reviews must include assessments of the associated risks and recommendations for their mitigation, when the agreed risk is exceeded.

5. Accounting results must be made available timeously, to meet operational reporting needs, including the provision of information for other management information systems, and to facilitate corrective action or investigation. A detailed report must be issued on each investigation, together with management’s response to rectify the problem. When completed, the plan and resulting action must be signed-off by the Competent Person.

6. Where provisional data has to be used to meet reporting deadlines, such as at month ends when analytical turn-around times could prevent the prompt issuing of the monthly report, clear procedures and levels of authorisation for the subsequent replacement of the provisional data with actual data must be defined. Where rogue data is detected, such as incorrect data transfer or identified malfunction of equipment, the procedures to be followed together with the levels of authorisation must be in place

7. The system must generate sufficient data to allow for data verification, the handling of metal/commodity transfers, the reconciliation of metal/commodity balances, and the measurement of accuracies and error detection, which should not show any consistent bias. Measurement and computational procedures must be free of a defined critical level of bias.

8. Target accuracies for the mass measurements and the sampling and analyses must be identified for each input and output stream used for accounting purposes. The actual accuracies for metal recoveries, based on the actual accuracies, as determined by statistical analysis of the raw data, achieved over a company’s reporting period must be stated in the report to the Company’s Audit Committee. Should these show a bias that the Company considers material to its results, the fact must be reported to shareholders.

9. In-process inventory figures must be verified by physical stock-takes at prescribed intervals, at least annually, and procedures and authority levels for stock adjustments and the treatment of unaccounted losses or gains must be clearly defined.

10. The metal accounting system must ensure that every effort is made to identify any bias that may occur, as rapidly as possible and eliminate or reduce to an acceptable level the source of bias from all measurement, sampling and analytical procedures, when the source is identified.