Reconciliation
Basic Objectives
Reconciliation has two main objectives:
- To improve the accuracy of the values recorded in the supply chain, and more particularly the tonnages and analyte values of the stockpiles and material movements over process flows.
- To appreciate the difference between recorded values in the supply chain and calculated values of the reconciliation process (reconciled values).
In both cases, values calculated in the reconciliation process are supposed to be more accurate than the recorded values for two reasons:
- The inputs of the calculations are the draft surveys and quality samples at the port location.
These values are more accurate because samples and draft surveys are generally measured with a higher precision and greater attention.
- Furthermore, draft surveys and samples at the port location are considered of a higher importance because they are quantities and quality data that are sold to customers.
Other Purposes of Reconciliation
Reconciliation is a topic largely explained in many documents related to mining. In these documents, other objectives are discussed. These are to:
- Measure performance of the operation against targets
- Ensure valuation of mineral assets is accurate
- Confirm grade and tonnage estimation efficiency
- Provide key performance indicators, in particular for grade control predictions
- Locate measurement errors, estimate their magnitude and minimise them so that the obtained data is as near as possible to the real data
- Validate instrumentation through the statistical reconciliation of data
- Deliver the best information about the process
- Manage quality data generation
- Provide transparency and objectivity of the production accounting in each area
- Decrease material losses and locate areas where losses are produced
- Determine if an instrument operates in the required accuracy range
- Consider the sampling error in material balances
- Validate the data obtained from the process
- Make budget and forecast deviation analysis
Balancing the Supply Chain
Reconciliation is the process of adjusting recorded values using the basic equation of stockpile locations:
Closing Balance - Opening Balance = Inputs - Outputs
Another completely different model is to consider the supply chain as a complete system: instead of adjusting location by location, all the locations are considered at the same time, and all the recorded values used (amounts of material transported, stockpile balances and analyte grades).
In this balancing model, the supply chain is represented as a system of N equations and M recorded variables.
The N equations are the equations:
(Closing Balance - Opening Balance = Inputs - Outputs) for each location
The M recorded variables are the amounts of material transported, the stockpile balances and analyte grades.
This model supposes that an accuracy level is defined for each recorded value. Note that this method of recording a value is more in line with a scientific approach of recording surveys and samples. From a scientific point of view, data should always be recorded with accuracy measures.
To reconcile the supply chain, the objective of the model is to find for each recorded variable, a balanced variable, complying with the N equations and as close as possible from the recorded associated variables.
In a practical interpretation, the aim is to look for reconciliation or balanced variables that comply with all the equations of the supply chain and, at the same time, minimise the distance to recorded values.
