BACKGROUND Mould water treatment protects the system from corrosion and extent mould life, but it has also been shown to improve plant productivity, and quality if properly deployed. Nalco has continuously demonstrated these results throughout the world and recently a long-term customer documented this first-hand when they ran a series of competitive trials to see if they could quantify the benefits of the Nalco program. The customer is a leading international manufacturer of high- quality flat steel products. They produce 2 Million tons per year (tpy) through 2 VAI Slab Casters (each having 2 strands). These units are designated #4 and #6 Casting Machines. Their product ranges is carbon steels having a width of 800 mm to 1,850 mm. End-uses of this steel are primarily exposed applications and coated (galvanized) products. Also, the client exports a significant Optimizing Continuous Casting Water Systems for Steel Customer in Russia CH-1752E CASE STUDY – PRIMARY METALS eROI is our exponential value: the combined outcomes of improved performance, operational efficiency and sustainable impact delivered through our services and programs. CUSTOMER IMPACT Improved productivity by 80,000 tons per year of steel produced, meaning the 4% in comparison to the competitive trials Improved product quality and minimised corrosion rate ECONOMIC RESULTS Increased profits of over $4.000.000 percentage of their slabs to their overseas rolling operations or sells them in the market. Both Casters are designed with the Machinery and Mould Circuits being inter-connected in a closed loop. These designs are generally more prone to high water usage due to machine coupling leaks, or hose leaks in the machinery side and can become problematic in treatment. Nonetheless during the Nalco tenure, critical water parameters had been in specification. Typical, Nalco maintained iron levels below 0.5 ppm – and circuit wide corrosion was <0.05 mm/year (2 mpy). While the client has repeatedly told Nalco that their business drivers were Total Cost of Operation (TCO) decrease, and improved Steel production, we were informed that the Utility & Procurement Departments wanted to ensure they were getting the best “value in use” with Nalco so they selected two competitors to be tested in the systems. ASSETS e ROI SM
Transcript
BACKGROUND
Mould water treatment protects the system from corrosion and extent mould life, but it has also been shown to improve plant productivity, and quality if properly deployed.
Nalco has continuously demonstrated these results throughout the world and recently a long-term customer documented this first-hand when they ran a series of competitive trials to see if they could quantify the benefits of the Nalco program.
The customer is a leading international manufacturer of high-quality flat steel products. They produce 2 Million tons per year (tpy) through 2 VAI Slab Casters (each having 2 strands). These units are designated #4 and #6 Casting Machines.
Their product ranges is carbon steels having a width of 800 mm to 1,850 mm. End-uses of this steel are primarily exposed applications and coated (galvanized) products. Also, the client exports a significant
Optimizing Continuous Casting Water Systems for Steel Customer in Russia
CH-1752E
CASE STUDY – PRIMARY METALS
eROI is our exponential value: the combined outcomes of improved performance, operational efficiency and sustainable impact delivered through our services and programs.
Customer ImpaCt
Improved productivity by 80,000 tons per year of steel produced, meaning the 4% in comparison to the competitive trials
Improved product quality and minimised corrosion rate
eConomIC results
Increased profits of over $4.000.000
percentage of their slabs to their overseas rolling operations or sells them in the market.
Both Casters are designed with the Machinery and Mould Circuits being inter-connected in a closed loop. These designs are generally more prone to high water usage due to machine coupling leaks, or hose leaks in the machinery side and can become problematic in treatment. Nonetheless during the Nalco tenure, critical water parameters had been in specification. Typical, Nalco maintained iron levels below 0.5 ppm – and circuit wide corrosion was <0.05 mm/year (2 mpy).
While the client has repeatedly told Nalco that their business drivers were Total Cost of Operation (TCO) decrease, and improved Steel production, we were informed that the Utility & Procurement Departments wanted to ensure they were getting the best “value in use” with Nalco so they selected two competitors to be tested in the systems.
ASSETS
eROISM
CURRENT SITUATIONThe trial period did not occur at one time, but rather Caster #4 and #6 ran separate competitive trials over 10-month period. Comparison levels of system Iron levels and corrosion rates were monitored, before, during and after the completive trials to evaluate the relative performances of each supplier.
The first Trial started on Caster #4. As Figure 1 shows the corrosion rate began to increase as soon as the alternative program was introduced. It remained higher during the entire period.
Similarly as the corrosion rate increased the level of soluble iron in the system increased (see Figure 2).
As this trial was ongoing at #4, a second company’s evaluation on Caster #6 began with similar results of higher levels of Iron and corrosion in the system (Figures 3 & 4).
During this period of competitive evaluations, the heat exchanges also had visible signs of iron deposition (Figure 5), reducing cooling capacity and thereby contributing to excessive corrosion rates.
Note: The build-up on the HX plates was not evident before or after the trial while Nalco was managing the systems.
RESULTS AND CONCLUSIONS After the start of the competitive trials, the cold rolling mill (CRM) began to see a spike in the level of surface defects. These were primarily blisters (scabs) and cracks (Casting Defects), but there were other defects as well.
Nalco Research in mould treatment and the development of our Cast Clean™ Program has documented that excessive corrosion and soluble iron in the system contributes to increase mould wear (and excess copper costs) and CRM surface defects. These findings have been documented in two AIST Convention Papers and at many Steel Plants over the last several years. Succinctly, Nalco Research findings show that deposition of iron onto the cold mould face changes the thermal conductivity of the mould (See Figure 7) resulting in a greater frequency of surface defects.
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Following excellent system analytical control and proper treatment guidelines, the local team was able to maintain corrosion rates of < 0.05 mm/year (2 mpy) and iron levels at 0.5 ppm. As a result the performance during the Nalco management period of the system had a defect rate 4% below the competitors’ trials.
These results clearly demonstrated that the Nalco solution had a significant impact on Plant yield and quality. Industry benchmark indicates that a 1% in quality
Thermal Conductivities of Substances that Deposit on Mould Coppers (Watt/meter*K) [W/m*K] [W/m2*K] Copper 415 Calcium Carbonate 2.6 Chrome 93.9 Calcium Sulphate 2.2 410 Stainless Steel 24.9 Calcium Phosphate 3.8
Carbon Steel 55.4 Fe3O4 3.1
Tenurite (Copper II Oxide) 17.6 Fe2O3 0.6
Copper II Carbonate Biofilm 0.7
improvement will save a plant over one million Dollars! Clearly the performance at this customer demonstrated exceptional results in quality and prime yield.
Nalco Research Department works to improve water treatment in the mould and these trials are further evidence of our commitment to the Global Steel Industry and our desire to deploy the best known practices for water treatment control.
Figure 6 - Cold Rolled Defects
Figure 7 - Thermal Conductivity of Typical Mound Deposits
Due to the documented performance advantages of the Nalco offering, the customer has informed Nalco that no further external evaluations will be considered.
