Benefits

• Stainless steel: between € 20 and 50 per ton of steel
• Knowledge aggregation of several sites in one common tool
• SCOOP Stainless Benefits Explained

Description

SCOOP for stainless steel is dedicated to the refining of stainless steel using duplex or triplex processes. As for SCOOP Minimill, SCOOP Stainless includes the possibility of multiple sites sharing the same inventory (scraps and other raw materials) for common purchasing while each site can have one or multiple flows.

SCOOP for stainless steel is adapted to different converter types (Argon Oxygen Decarburization, Vacuum Oxygen Decarburization) and combinations thereof. It integrates the different production phases: Electrical Arc Furnace (EAF), Converter (CV) and Ladle Metallurgy (LM). It computes different losses such as dust developed upon loading of raw materials, smoke development during melting, decarburization and deslagging and the imperfect separation slag and steel during deslagging. SCOOP also values the metallic content of the different losses that can be recovered (recoveries).

Some of key optimization levers used by the SCOOP model for Stainless Steel includes the build-up (the quantity of materials that is added at the converter versus the furnace) and the intermediate steel composition (the content of elements like Ni, Cr, Mo and other raw materials in the steel after the electrical furnace and before the converter).

The EAF module covers

• Loading of baskets and bunkers
• Time under electric arc
• O2 and N2 blowing
• Reduction
• Deslagging

Graphically, presented as:

The converter module includes

• Loading of raw materials via bunker
• Lance and tuyere blowing of Ar, O2, N2
• Reduction/desulphurization
• Deslagging

Dependent on installation type and grade type, the converter module includes multiple oxidation steps. At each oxidation step, loading and blowing is repeated.  The converter process is finalized by the reduction/desulphurization step. The process is illustrated hereafter:

The Ladle Metallurgy module includes

• Loading of raw materials (scraps, ferroalloys, fluxes)
• Finishing steel composition

SCOOP Stainless offers the opportunity to compute raw material prices given public element prices (e.g. Mo, Ni, Cu, Ti, Cr, Fe, …) , analysis data and price contract parameters or uses direct prices. In combination with the ‘limit marginal price’ functionality, it is a strong asset to prepare raw material purchases.

Inputs 

• Active flows and sites
• Period length
• Grades: definitions and quantities
• Raw materials (internal or external scraps and recuperation materials, additions) with purchase cost, chemical analysis, enthalpies and densities
• Sourcing (prices and availabilities)
• Element prices and price contract parameters (valuation rates, bonus, finance cost, …).
• Fixed and Variable costs (operating costs, demurrage, electricity, slag treatment…) re-use and recycling
• Technical process parameters (chemical, productivity, thermal) for chain dimensioning and stage specific dimensioning

Constraints

Chain dimensioning

• Steel grade definitions (min-max)
• Raw material availabilities (min-max)
• Build-up of liquid steel along the chain (EAF-CV-LM) (min-max)

Stage specific dimensioning
EAF

• Charging  (°/°°)
• Volume of baskets, capacity of furnaces
• Oxygen balance
• Energy balance
• Chemical energy
• Thermal energy requirements
• Temperature profiles
• Decarburization
• Alkalinity indices
• Productivity
• Intermediate steel analysis (min-max)

Converter (e.g. AOD or VOD)

• Charging (°/°°)
• Process design (number of blowing steps)
• Bunker capacity
• Temperature profiles
• Decarburization profiles
• Distribution of oxygen over different oxidizing metallic elements
• Lance vs tuyeres blowing speeds/gas mixes
• Reduction rates
• Alkalinity indices
• Slag composition
• Oxygen balance
• Energy balance
  • Chemical energy
  • Thermal energy requirements
• Productivity
• Intermediate steel analysis (min-max)

Ladle Metallurgy

• Charging (°/°°)
• Productivity

Output 

• Cheapest feasible mix of raw materials
• Composition and quantities of steel, slag and loss
• Optimal composition of steel at EAF, CV and LM output
• Material input at each converter phase
• Steel characteristic targets at each phase of converter
• Limit Marginal Price (LMP) (~Value in use)