Process

Technology trends in grinding systems

Published

6 years ago

January 4, 2019

admin

This article discusses the recent trends in varying requirements, critical selection criteria for selection of grinding technology for a given application.

The grinding technology for cement production has evolved over period of last 100 years, matching with the trends of types and specifications of cements, scaling up in plant capacities, changing limestone and solid fuel usage. Grinding processes consume over 65 per cent of total electrical energy requirement of a cement plant. Over the period, technology suppliers have taken initiatives to innovate and improvise the configuration of grinding circuits to match with the changing characteristics of raw materials, cement specifications, etc. and meet the expectations of end users.

The grinding operation is an important process in cement manufacturing, which decides the following critical plant performance indices.

Product quality and consistency
Specific electrical energy consumption (kwh/t of cement)
Hence, from the conceptualisation of a concept to commissioning and to sustain the operational efficiencies of the plant, the selection of technology for grinding systems plays a major role.

Since the start of Portland cement production, over 100 years, the technology developments have taken place in grinding of raw materials, solid fuels, clinker and additives (GBF slag, fly ash etc) in the following chronological order:

1. Ball mills
2. Vertical roller mills
3. Roll press mills

These three types of technologies differ in what type of forces are applied to achieve the desired for particle surface (or fineness) generation. In case of Ball mills, the forces are compression, impact and attrition, in the case of vertical roller mills, the forces are Compression and attrition and in the case of roller press and horizontal roller mills, the force is only compression.

The main challenges industry posed to the technology suppliers to come out with the innovating solutions for grinding process are as follow:

Production of various types of cement as per market demand, from same grinding system.
Uniform and consistent product quality (surface area/particle size distribution) Large scale of operations (>5 million tonne per annum)
Highest energy efficient plants for blended cement at higher specific surface >4000 Blaine.
Grinding technology to suit varying feed characteristics (Moisture, two or more components of different grindabilities and feed sizes)
Less availability of waste heat required for operation of grinding systems (due to Higher thermal achieved in Kiln systems and waste heat recovery based power generation)
Compactness of grinding plants due for optimised plant layouts
Reliability of high capacity mills with a single drive
Plant operation with state-of-the-art process and control system with minimum operator intervention

Design of plants for shifting from one location to other to market demand centres
Technology suppliers have responded to these challenges by providing solutions customising the standard designs by modifying the grinding circuits and also developing reliable systems for meeting the higher capacity requirements.

Some of the trends observed in the industry are as follows:

Ball mill systems
Except for small capacity plants, ball mill systems are not preferred option for any new projects. However, in few projects, the concept of starting initially with ball mill system (with minimum CAPEX) and later capacity expansion and for savings in energy, upgrading the system with roller press or vertical mill for pre-grinding of clinker is considered.

Most of the technological innovations are taking place in existing plants with the objectives of increasing the capacity and energy efficiency and to produce finer blended cements (especially PPC). Some the innovations implemented by industry are:

All the high capacity ball mill systems currently in operation are closed circuit with high efficiency dynamic separators.
Central drive mill systems for better reliability.
For upgraded systems, roller press or vertical mill for pre-grinding clinker is incorporated in the closed circuit with or without a closed circuit with high efficiency separator/Mogenson sizers.
In case of up gradation with clinker pre-grinding system, conversion of ball mill to a mono-chamber is carried off in many existing installation.
All new installation with pregrinding is coming with Mono chamber ball mills. For fly ash usage for PPC production, Classifiers are provided for fly ash for separation of fine fly ash, which goes as product and Coarse fly ash is only fed to ball mill inlet.

Vertical roller mill systems
Vertical roller mills are most versatile equipment, which can handle all the type of raw materials, solid fuels and additives used in cement process. The compactness of the VRM systems makes the plant layouts very compact.

Multi drive systems for Vertical Roller Mills (e.g. MVR of Pfieffer or QMS-RD of Polysius) has become a major feature, which eliminated the risk with failure of high HP gearboxes for VRMs. This has made designing the VRMs for very high capacity cement grinding systems (one mill of capacity 3 MTPA).
VRM systems are designed for combined or separate grinding of blended cements
Modular design grinding plants for production (capacity up to 3,00,000 tonne per year) by start-up units or end users at construction sites.
High efficiency dynamic separators
VRM suppliers have also now come out with designs utilising water spray only for starting the mill for PPC grinding. However, these designs are yet to proven for different clinker granulometry/hardness.

Roller press systems
The technology development for roller press systems has started for application as pre-grinding of clinker for cement production in open circuit mode to increase the energy efficiency of ball mills. Over the last 30 years, with the developments of technology and material sciences, the roller press technology has now evolved as one of the most energy efficient grinding systems for raw meal and cement grinding. Especially with the advent of V-type static separators and High efficiency dynamic separators, the roll press technology is offering finish mode grinding systems, thus completely eliminating the ball mills in grinding circuits.

For finish grinding mode, two circuit configurations of Roller press systems are installed in cement plants. Both these circuits differ in the location of location of static and dynamic separators in the circuit. Depending on the material characteristics (moisture, grindability and % fines in feed, etc.) and space availability, the technology suppliers offer the most suitable system for a given customer requirement.

Horizontal roller (Horo) mill systems
The technology development of Horizontal Roller Mills (HORO mills) was done in 1990s. However due to the competing technologies of roller press and vertical roller mills, this technology has not become popular in the industry.

The Horo mill covers all the applications of cement manufacture i.e. raw, solid fuel and cement grinding. Industrial operations have shown energy savings ranging from 35-40 per cent as compared to ball mills. There is no requirement of water spraying inside the mill. Due to low residence time inside the mill, change over time is about 5-10 minutes from one product to another (cement to slag or raw meal). Since the Horo mills have compact integrated drives like those of ball mills, they are easy to install within a limited space. The system includes auxiliary equipment such as the classifier, filter and bucket elevator. One of the advantages of a Horo mill is production flexibility that is, in one mill raw meal and cement can be produced at different periods, thus an opportunity in savings in CAPEX and plant layout optimisation.

Separate grinding vs inter-grinding of blended cements
At higher proportions of usage of slag or fly ash for blended cements, with inter-grinding, the cement quality becomes inconsistent and also the energy efficiency of grinding process get affected. This is on account of different characteristics such as feed size, moisture of feed components fed to the mill. Hence to overcome these problems, the Technology suppliers offer two mills (one each for OPC and slag) or same mill circuit, which can grind OPC and slag at different times, with a separate storing and mixing arrangement. From the view of operational efficiency, two mill solutions will be more preferred as each mill is designed specifically for OPC or Slag to achieve best particle size distribution and energy efficiency levels. For PPC, inter-grinding of OPC and coarse fly ash is done in all types of grinding circuits, with fines removal of fine fly ash in in-built (in case of VRM) or dynamic separator of the mill systems. Technology suppliers of vertical roller mills, roller press and Horo mill offer common grinding systems for separate grinding.

Technology of Modular designs
Modular grinding systems address the long gestation periods of projects of first time cement producers with low initial investments, without sacrificing outputs or reliability. Technology Suppliers have been developing modular solutions in an effort achieve this objectives over the last few years.

Modular system is designed as a portable solution for companies in need of quick start of production or increasing capacity at short notice to meet the peak market demands. Modular designs are available to grind Fuels, Raw grinding & Cement (or additives such as slag, limestone).

The advantages of the modular design are:

Proven technology of major equipment
Low cost of transportation of equipment to site
Low delivery times of equipment (<9 months)
Low investment risk (as entry capacity are smaller), fast market entry (<11 months)
Low construction and Installation periods (<6 months)
Compact design with minimum land usage.

The systems are designed for easy dismantling (except civil foundations) of plant in modules and transport them and relocate at different location within a shortest possible times. The typical capacities of modular designed grinding systems are: for raw mill (<50 tph) and Slag (<30 tph) and cement (<40 tph).

This technology allows the customer to alternate, interchangeably, between the types of material to be ground. As the materials in terms of grindability and abrasiveness are different, these Mills are designed for small to high throughput rates to comply with customer specifications. The grinding system with high efficiency classifier significantly reduce power consumption compared to conventional ball mills, to make these small companies to be competitive with large companies with respect to Product quality and Costs.

In existing cement plants, where there are marginal shortfalls in grinding systems results meeting the peak market demand for cement, a modular grinding system can be considered as one of the options for capacity debottlenecking initiatives, with shortest possible time of implementation.

Process control & automation
Over the last 15 years, cement industry has realised, in order to achieve uniform quality of Product, to operate at high energy efficiency and plant availability, the Process control in grinding circuits should be given the same importance as is given to Kiln system with latest trends in Industrial automation systems. The PLC based automation system is so common even in mill system of capacities as low as 30 tph. The Volumetric measurement systems for dosing of feed components go mill systems have become obsolete and replaced by gravimetric systems such as belt weigh feeders, Rotary Weigh feeders/Impact flow meters, etc.

Online condition monitoring systems for high capacity gearboxes of VRMs by remote monitoring by OEM suppliers through internet communication has become a standard. On-line Particle size analysers are also installed in many of the t abroad and few plants in India for Process control in grinding systems and this is one the developments. Very large capacity grinding units are provided with expert systems for optimised operation of plant.

Conclusion
Even though ball mill systems are still preferred for lower capacity (up to 1 mtpa) due to less CAPEX and 100 per cent indigenous sourcing of equipment, the trend of the industry in future is to go for vertical mill or roll press systems. VRM with multi drive systems are proven in the industry, which makes it possible to go for single mills for raw grinding and cement grinding for capacities 10,000 tpd and above. cement industry is also looking for grinding solutions without water spray into the system, which is a essential requirements for VRMs for using water spray for raw materials with low moisture (1-2 per cent) levels and in clinker grinding systems.

The grinding systems suppliers should take into account as the industry are in the process of installing WHR power generation systems, no high temperature waste gases (>200 degree Celsius) are available for grinding processes nor the grinding units can afford to provide hot gases for cement grinding on continuous basis.

Modular grinding systems have low gestation period for project implementation to cater to local cement demand is one more attractive technology for cement industry growth in future.

About the author:
YV Satyamurthy is a consultant for cement and mineral industries with more than 35 years of working experience in ACC Limited and Reliance Cement in functional areas of process and project engineering, project management and training.

Process

Price hikes, drop in input costs help cement industry to post positive margins: Care Ratings

Published

3 years ago

October 21, 2021

admin

Region-wise,the southern region comprises 35% of the total cement capacity, followed by thenorthern, eastern, western and central region comprising 20%, 18%, 14% and 13%of the capacity, respectively.

The cement industry is expected to post positive margins on decent price hikes over the months, falling raw material prices and marked drop in overall production costs, said an analysis of Care Ratings.

Wholesale and retail prices of cement have increased 11.9% and 12.4%, respectively, in the current financial year. As whole prices have remained elevated in most of the markets in the months of FY20, against the corresponding period of the previous year.

Similarly, electricity and fuel cost have declined 11.9% during 9M FY20 due to drop in crude oil prices. Logistics costs, the biggest cost for cement industry, has also dropped 7.7% (selling and distribution) as the Railways extended the benefit of exemption from busy season surcharge. Moreover, the cost of raw materials, too, declined 5.1% given the price of limestone had fallen 11.3% in the same aforementioned period, the analysis said.

According to Care Ratings, though the overall sales revenue has increased only 1.3%, against 16% growth in the year-ago period, the overall expenditure has declined 3.2% which has benefited the industry largely given the moderation in sales.

Even though FY20 has been subdued in terms of production and demand, the fall in cost of production has still supported the cement industry by clocking in positive margins, the rating agency said.

Cement demand is closely linked to the overall economic growth, particularly the housing and infrastructure sector. The cement sector will be seeing a sharp growth in volumes mainly due to increasing demand from affordable housing and other government infrastructure projects like roads, metros, airports, irrigation.

The government’s newly introduced National Infrastructure Pipeline (NIP), with its target of becoming a $5-trillion economy by 2025, is a detailed road map focused on economic revival through infrastructure development.

The NIP covers a gamut of sectors; rural and urban infrastructure and entails investments of Rs.102 lakh crore to be undertaken by the central government, state governments and the private sector. Of the total projects of the NIP, 42% are under implementation while 19% are under development, 31% are at the conceptual stage and 8% are yet to be classified.

The sectors that will be of focus will be roads, railways, power (renewable and conventional), irrigation and urban infrastructure. These sectors together account for 79% of the proposed investments in six years to 2025. Given the government’s thrust on infrastructure creation, it is likely to benefit the cement industry going forward.

Similarly, the Pradhan Mantri Awaas Yojana, aimed at providing affordable housing, will be a strong driver to lift cement demand. Prices have started correcting Q4 FY20 onwards due to revival in demand of the commodity, the agency said in its analysis.

Industry’s sales revenue has grown at a CAGR of 7.3% during FY15-19 but has grown only 1.3% in the current financial year. Tepid demand throughout the country in the first half of the year has led to the contraction of sales revenue. Fall in the total expenditure of cement firms had aided in improving the operating profit and net profit margins of the industry (OPM was 15.2 during 9M FY19 and NPM was 3.1 during 9M FY19). Interest coverage ratio, too, has improved on an overall basis (ICR was 3.3 during 9M FY19).

According to Cement Manufacturers Association, India accounts for over 8% of the overall global installed capacity. Region-wise, the southern region comprises 35% of the total cement capacity, followed by the northern, eastern, western and central region comprising 20%, 18%, 14% and 13% of the capacity, respectively.

Installed capacity of domestic cement makers has increased at a CAGR of 4.9% during FY16-20. Manufacturers have been able to maintain a capacity utilisation rate above 65% in the past quinquennium. In the current financial year due to the prolonged rains in many parts of the country, the capacity utilisation rate has fallen from 70% during FY19 to 66% currently (YTD).

Source:moneycontrol.com

Process

Wonder Cement shows journey of cement with new campaign

Published

3 years ago

October 21, 2021

admin

The campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV…

ETBrandEquity

Cement manufacturing company Wonder Cement, has announced the launch of a digital campaign ‘Har Raah Mein Wonder Hai’. The campaign has been designed specifically to run on platforms such as Instagram, Facebook and YouTube.

#HarRaahMeinWonderHai is a one-minute video, designed and conceptualised by its digital media partner Triature Digital Marketing and Technologies Pvt Ltd. The entire journey of the cement brand from leaving the factory, going through various weather conditions and witnessing the beauty of nature and wonders through the way until it reaches the destination i.e., to the consumer is very intriguing and the brand has tried to showcase the same with the film.

Sanjay Joshi, executive director, Wonder Cement, said, "Cement as a product poses a unique marketing challenge. Most consumers will build their homes once and therefore buy cement once in a lifetime. It is critical for a cement company to connect with their consumers emotionally. As a part of our communication strategy, it is our endeavor to reach out to a large audience of this country through digital. Wonder Cement always a pioneer in digital, with the launch of our IGTV campaign #HarRahMeinWonderHai, is the first brand in the cement category to venture into this space. Through this campaign, we have captured the emotional journey of a cement bag through its own perspective and depicted what it takes to lay the foundation of one’s dreams and turn them into reality."

The story begins with a family performing the bhoomi poojan of their new plot. It is the place where they are investing their life-long earnings; and planning to build a dream house for the family and children. The family believes in the tradition of having a ‘perfect shuruaat’ (perfect beginning) for their future dream house. The video later highlights the process of construction and in sequence it is emphasising the value of ‘Perfect Shuruaat’ through the eyes of a cement bag.

Tarun Singh Chauhan, management advisor and brand consultant, Wonder Cement, said, "Our objective with this campaign was to show that the cement produced at the Wonder Cement plant speaks for itself, its quality, trust and most of all perfection. The only way this was possible was to take the perspective of a cement bag and showing its journey of perfection from beginning till the end."

According to the company, the campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV. No other brand in this category has created content specific to the platform.

Process

In spite of company’s optimism, demand weakness in cement is seen in the 4% y-o-y drop in sales volume. (Reuters)

Published

3 years ago

October 21, 2021

admin

Cost cuts and better realizations save? the ?day ?for ?UltraTech Cement, Updated: 27 Jan 2020, Vatsala Kamat from Live Mint

Lower cost of energy and logistics helped Ebitda per tonne rise by about 29% in Q3
Premiumization of acquired brands, synergistic?operations hold promise for future profit growth Topics

UltraTech Cement
India’s largest cement producer UltraTech Cement Ltd turned out a bittersweet show in the December quarter. A sharp drop in fuel costs and higher realizations helped drive profit growth. But the inherent demand weakness was evident in the sales volumes drop during the quarter.

Better realizations during the December quarter, in spite of the 4% year-on-year volume decline, minimized the pain. Net stand-alone revenue fell by 2.6% to ?9,981.8 crore.

But as pointed out earlier, lower costs on most fronts helped profitability. The chart alongside shows the sharp drop in energy costs led by lower petcoke prices, lower fuel consumption and higher use of green power. Logistics costs, too, fell due to lower railway freight charges and synergies from the acquired assets. These savings helped offset the increase in raw material costs.

The upshot: Q3 Ebitda (earnings before interest, tax, depreciation and amortization) of about ?990 per tonne was 29% higher from a year ago. The jump in profit on a per tonne basis was more or less along expected lines, given the increase in realizations. "Besides, the reduction in net debt by about ?2,000 crore is a key positive," said Binod Modi, analyst at Reliance Securities Ltd.

Graphic by Santosh Sharma/Mint
What also impressed analysts is the nimble-footed integration of the recently merged cement assets of Nathdwara and Century, which was a concern on the Street.

Kunal Shah, analyst (institutional equities) at Yes Securities (India) Ltd, said: "The company has proved its ability of asset integration. Century’s cement assets were ramped up to 79% capacity utilization in December, even as they operated Nathdwara generating an Ebitda of ?1,500 per tonne."

Looks like the demand weakness mirrored in weak sales during the quarter was masked by the deft integration and synergies derived from these acquired assets. This drove UltraTech’s stock up by 2.6% to ?4,643 after the Q3 results were declared on Friday.

Brand transition from Century to UltraTech, which is 55% complete, is likely to touch 80% by September 2020. A report by Jefferies India Pvt. Ltd highlights that the Ebitda per tonne for premium brands is about ?5-10 higher per bag than the average (A cement bag weighs 50kg). Of course, with competition increasing in the arena, it remains to be seen how brand premiumization in the cement industry will pan out. UltraTech Cement scores well among peers here.

However, there are road bumps ahead for the cement sector and for UltraTech. Falling gross domestic product growth, fiscal slippages and lower budgetary allocation to infrastructure sector are making industry houses jittery on growth. Although UltraTech’s management is confident that cement demand is looking up, sustainability and pricing power remains a worry for the near term.