Integrated Iron and Steelworks "STEELSTRAT"
Optimisation of “Pre-Tax Net Present Value” techno-economic planning of Large Integrated Mining and Metallurgical Complexes with specific reference to Steel Plants
Scale Linear Programming Solutions” formulated a strategic planning optimisation
model based on LINEAR and MIXED INTEGER PROGRAMMING and RECURSIVE TECHNIQUES of
• in-house iron ore resource (mines)
• external iron ore resources
• in-house coking coal resources (mines)
• external coking coal resources
• external coke resources
• DRI plants
• SINTER plants (production vs. basicity curve)
• coking coal plants/ovens/batteries
• BLAST FURNACES (coke CSR curve & heat balance)
• BASIC OXYGEN FURNACES
• ELECTRIC ARC FURNACES
• continuous casting devices and the mills (flat products and profiles)
• MARKETS i.t.o. SALES VOLUMES per generic product group,
SELLING PRICES and EXCHANGE RATES
• IRON METAL SCRAP balances
ALL THE ABOVE UNITS ARE LINKED TO FORM A LARGE INTEGRATED MINING AND METALLURGICAL STEEL MANUFACTURING COMPLEX.
The model links the resources through all the above
units right up to the markets and produces the MAXIMUM PRE-TAX NET PRESENT
VALUE BUSINESS PLAN over multi-time periods of “n” months to “m” years. In
doing the above, the model takes the technical constraints into account :- slag
chemistry, product and intermediate product analyses (e.g. DRI product, sinter
product and hot metal), gas analysis, throughput capacities etc. etc.
The model is detailed down to the levels of stoicheiometry, slag chemistry, metallurgical balance and heat balances and is able to calculate the OPTIMAL mix of raw materials that will satisfy ALL THE DOWNSTREAM PROCESSES. It takes pollution restrictions as well as desulphurisation into account. It takes stocks into account as well and this allows the planner to optimally schedule stocks over time and phase it in with production. This is most helpful during “shut-down / start-up” decision making phases.
The system solves on a fast PC in under 5 minutes and produces apart from the OPTIMAL (NPV) TECHNO-ECONOMIC PLAN, an INCOME STATEMENT and reports on marginal costs/profits on the bottle-neck activities and plants. In periods of business contraction, the model will determine plans that will ensure that harm to cash flow is minimised.
This approach, using the latest mathematical optimisation technology, is extremely well equipped to aid in decision support for longer term planning scenarios, e.g. CAPITAL EXPANSION motivations, evaluation of ALTERNATIVE TECHNOLOGIES eg sinter versus DRI versus PELLETS etc., evaluation of different COKING COAL BLENDS, final product SALES MIX RATIONALISATION and many more applications.
This approach avoids sub-optimisation in the planning processes and the model serves as an efficient decision support tool for strategic, medium term and contingency planning.
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