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Identifying the volumes and points of origin of the waste and the causes of the waste and emissions
Developing a basis for an evaluation and forecasting of future developments
Providing strategies to improve the general situation.
The waste and emission issues of a company occur at the points of production where materials are used, processed or treated. In finding a strategic solution to these issues it is essential to record the current material flows which will indicate points of origin, volumes and causes of wastes and emissions. A material flow analysis incorporates the analyses of the substances used to determine its composition and economic value and future developments are also forecasted. The implementation of an information system will allow management to track material flows within the company and direct them in order to ensure their efficient use.
4.4.1.1 STEP 1: DRAW A MATERIAL FLOWCHART
Drawing a Material Flowchart consists of four core elements, namely:
Define the objective of the material flow analysis and the parameters to be monitored
Define the scope of the balance
Define the time period of the balance
Identify and define process steps 4.4.1.1 a) Defining parameters
One of the primary objective of a material flow analysis is to retrace the flow of either goods, chemical compounds or a single element through the company based on different criteria (volumes, cost, risk, safe disposal, etc.). This criterion needs to be decided upon in the beginning of this process.
If the objective is not already defined it is best to start with the material flow analysis of the company in its entirety (material balance at a company level) by performing a global input/output analysis which should contain the following information:
The materials used in the company
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Amount of materials processed
The economic value of the materials
The quantities of waste and emissions generated by the process and disposed of
A list of all raw materials, processed materials, products, emissions and energy sources is generated using accounting and stock keeping records. In identifying priorities the identified material flows can be ranked according to their value and toxicity. Most commonly a detailed analysis will be conducted on expensive and ecologically problematic materials.
4.4.1.1 b) The scope of the balance
The scope of the balance depends on the objectives of the analysis and can either encompass the company as a whole or be restricted to individual processes. It is standard to perform a material balance at a company level to identify a focus area and thereafter the process is divided into single steps.
4.4.1.1 c) The balance period
It has been proven successful to select a specific time span for the balance which could be a production batch, production week, a month or even a year.
4.4.1.1 d) Identifying and defining production steps
In this phase the processes are divided and into sections and illustrated in the form of a flowchart.
The flowchart can be based on equipment or activities, on profit centres, or production units.
Production steps are symbolized using rectangles and material flows using arrows. Thereafter all relevant data (such as components, volumes, data sources, values etc.) should be indicated on the flowchart. Other important data (such as temperatures, pressures, batch sizes etc.) should also be documented. This flow diagram is aimed at gaining a clear understanding of the process.
49 4.4.1.1 e) Preparing the process flowchart:
Prior to preparing the process flowchart the boundaries of the process needs to be decided and this depends on the available information. Thereafter a list of activities in the process are to be generated and arranged in sequence. The sequence of activities should be discussed with the company employees (workers or supervisor) to confirm that it is correct. The process flowchart is then drawn and reviewed by company employees and other relevant stakeholders to ensure that it is accurately drawn.
4.4.1.1 f) Identifying the materials, quantities and the hazards involved in the process:
Identify the materials involved in each step of the process and indicate them on the flowchart
Identify the quantities of the materials involved in each step of the process and indicate them on the flowchart
4.4.1.2 STEP 2: CREATE A MATERIAL BALANCE
The core principle applied in a material balance is the conservation of mass, which states that mass can never be created nor destroyed but only transferred from one volume to another (Angelo, 2009). In other words all raw and processes materials have to either leave as product, waste or emissions.
The data required to create a material balance can be acquired from log books, production data acquisitions, individual measurements, routine measurements, documentation of equipment and the production department and also by calculating and estimating. Data regarding raw and processed materials can be obtained from the accounts department while data regarding the process can be obtained from the production planning and control departments. If for any reason the data is not retrievable or available then either measurements have to be carried out or estimates relied upon. A good estimate with the accuracy of 80 – 90 % is generally sufficient and is preferable to having no balance at all.
50 It is usual for output data to be detailed on control sheets, therefore flows of some materials can be retraced from their point of entry through the process right to the point of output.
4.4.1.3 STEP 3: CONSIDER OPTIONS
The final step entails the interpretation of the flowchart. The material paths are retraced and key efficiency and performance ratios for each production step as well for the company as a whole are calculated. In order to do this, waste generation points have to be determined and the ratio between raw materials and waste calculated. The calculated or real efficiency can be compared to the previously projected efficiency. The weak points in the system can be identified by comparing the real efficiencies to the projected efficiencies. The weak points then ranked and then analysed.
Thereafter discuss these weak points should be discussed with the relevant personnel in the company. By updating data, material use and material flows regularly, an instrument for technical control is created.