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Case Study - A 2000 TPD PPC Operation in India
This plant produces 2000 TPD of PPC through a 90 TPH cement grinding mill. The plant is located very close to a thermal power plant and has access to abundant fly ash. The landed cost of fly ash for the plant is quite low as the only price to pay is for the handling and transport of the ash. Thermal power plants in India are not allowed to sell their ash and are supposed to let cement producers lift it for free.
The content of fly ash is limited in PPC largely by its impact on the early age strength of the resulting concrete. STAREX thus offers a very complimentary property with its positive impact on cement strength.
After multiple tests conducted at lab scale and plant scale, the benefits of dosing STAREX in the cement mill were clearly established. The plant now feeds STAREX into the cement mill continuously along with clinker, fly ash and gypsum.
The impact of STAREX on cement quality, fly ash content, and mill output is summarized in the table below.
STAREX Dosage Mill Output Clinker Gypsum Fly Ash Blaine Residue Compressive Strength in MPa
% TPH % % % M2/Kg 45 Mic 90 Mic 1-Day 3-Day 7-Day 28-Day
Blank 90 75 4 21 339 30 13 11 25 34 51
0.05% 95 70 4 26 350 20.8 5 12 27 35 53
As seen above, STAREX has increased fly ash content by 5% and improved cement performance at all stages of strength development. The mill output has also increased by around 5%. These physical benefits in turn have converted into commercial benefits reduced cost of production, improved market response, and higher cement realization.
Reduction in Cost of Production
The addition of STAREX allows the plant to add 5% more fly ash while reducing the clinker content by the exact amount. This, combined with power saving due to higher mill output, not only completely offsets the cost of STAREX but also offers additional cost savings.
Improved Market Response
Even after an increase in fly ash content and reduction in clinker content, the plant is successfully able to deliver to an improved cement quality. The strength at all ages is higher and is gradually improving the brand image of the cement produced by this plant.
With the supply glut expected over the next couple of years in the Indian cement industry, the improved brand image should keep the health of this cement plant's business in good condition.
Higher Cement Realization
STAREX has helped the plant successfully increase the cement mill output by around 5%. This in turn has a direct impact on the company's realization and income.
Reduced Carbon Footprint
Apart from the above mentioned benefits that directly impact the profits of the company, STAREX also delivers on a key environmental parameter, which is expected to gain increasing significance in the times to come - reduced carbon footprint per ton of cement production. Every ton of clinker produces 440 KG of CO2. A reduction in clinker content by 5% points in PPC translates into 22 KG of CO2 saved per ton of cement.
This turns into 13,200 ton of reduced CO2 emission over a year for the plant (based on 2000 TPD production and 300 days of plant operation).
Dosing Mechanism
The plant has deployed a gravimetric dispenser with belt conveyor as recommended by Unisol Inc. for accurately dosing STAREX into the cement mill inlet. The dispenser is installed so that STAREX drops on the clinker weigh-feeder belt and goes into the mill inlet along with clinker.
The dispenser is equipped with a control panel and has been integrated with the DCS panel in the Central Control Room of the plant. Thus the STAREX dosage rate and feed can be centrally controlled.
A picture of the dispenser and its local control panel is provided below.
Dispenser with Hopper and Belt Conveyor Based Feeding System Control Panel of the Dispenser
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