Product development

Use of high MgO limestone in Portland cement manufacturing

Published

7 years ago

February 28, 2018

admin

GC Mishra and KN Bhattacharjee observe that if the MgO content is <2.0 per cent in the raw meal it is incorporate into the crystal structure and works like good mineraliser by improving the burnability, promoting the absorption of free lime and improve the formation of C3S and C4AF.
With depletion of high cement grade limestone, presently Indian cement industry is facing an acute cement raw material problem for smooth plant operation and manufacture of higher grade cement. Although India is bestowed with huge imestone resources the most of the limestone deposits in India presently available for cement manufacture are either marginal grade or low grade, whereas the demand for high grade limestone has been increased in recent years for anufacture of higher grade cements. Some of the cement plant starts with a simple limestone deposit with more or less uniform quality of limestone, with the consumption of the high grade limestone, the deposit converted in to intricate and left with very low heterogeneous grade some times dolomitic with high Magnesium oxide (MgO) content.
Hence a serious thought is essential not only for detailed exploration of limestone deposits to convert the resources to reserves (as per UNFC), but also for development of a cost effective dry beneficiation technique for up gradation the low and sub-marginal grade limestone in India and use of huge high MgO limestone to meet the increase demand of limestone in cement manufacture.Scenario of limestone deposits
Limestone being the prime raw materials for cement manufacture the growth of the cement industry depends on the availability of cement grade limestone. India is having huge limestone deposits distributing through out the geological stratigraphic horizon starting from Archaean to Tertiary formations. Thus, the quality variation of limestone from deposit to deposit is very wide in India. The geographical distribution of limestone deposits in India is also not uniform. Some of the States do not have any limestone deposits. It has been observed that more than 95 per cent of cement grade limestone deposits are concentrated in 10 states, although the cement grade limestone is occurring in 23 States in India.
The limestone deposits are not reported from Punjab, Mizoram, Goa, Sikkim and Tripura, whereas Haryana, Manipur, West Bengal, Andaman and Nicobar Islands have very meager reserves not suitable for large capacity cement plants. Based on the prima-facie availability of freehold cement grade limestone deposits, there is very limited scope for further addition of cement manufacturing capacity in Kerala, Tamil Nadu, Bihar, Uttar Pradesh and Odisha. However, the States of Andhra Pradesh (including Telengana), Assam, Gujarat, Himachal Pradesh, Karnataka, Chattisgarh, Meghalaya and Rajasthan have potential for further creation of additional cement manufacturing capacity.
The qualitative and quantitative assessment of limestone deposits have been carried out by various central government, State Directorate of Geology and Mining and private companies. Based on the exploration data generated by these agencies at present the total cement limestone resource estimated by Indian Bureau of Mines (IBM) is 1,24,539.551 MT.
As per the quality of limestone, except limestone occurring in the Northeast, Gujarat, a few patches of Andhra Pradesh (including Telengana), Rajasthan and Madhya Pradesh most of the deposits are low grade, either having high silica content (SiO2 16-20 per cent) or high magnesia containing 6-12 per cent MgO or even more. These limestone can not use for manufacture of cement as such with the require beneficiation. Specially the production of sound cement from high MgO limestone is the biggest challenge.
Further, out of total limestone resources 1,24,539.91 MT, 30 per cent falls under the forest cover, restricted area and eco-sensitive zone, not permissible for exploitation. As a result further 34677.19 million tonnes of limestone are not available for the cement industries, although some of the deposits are best cement grade limestone. From the available remaining 89862.361 limestone resources cement grade limestone reserves is only 8,948.926 MT (UNFC Code (111), (121) and (122)) as per UNFC classification of mineral deposits.
Although the consumption ratio of limestone to cement has gone down in India due to production of more blended cement, the limestone quantity requirement for cement manufacture has increased 1.5 times in last 15 years. Further the demand for high grade limestone has been increased due to production of more 43 and 53 grade cements. It has been observed that the demand of high grade limestone increase the mines rejects further. The limestone requirement for production of 71.28 MT of clinker during 1997-98 was 106.92 million tonnes and in the year 2013-14 it has enhanced to 300.00 MT. From an estimate it has been seen that for production of 500 MT of Clinker (as anticipated) by the end of 2020 the limestone requirement will be around 700 million tonnes. Hence the detailed exploration and establishment of the limestone deposits , use of high silica and high MgO limestone in cement manufacture is the need of the hour.
If this trend persist the annual limestone requirement for production of 500 MT (as anticipated) of clinker by the end of the year 2020 will be around 700 MT. With this rate of consumption the present available limestone reserves of India can sustain only 40 years. (12th plan report)Effect of High MgO in Portland cement
For production of Portland cement the limiting value of MgO in case of cement grade limestone is 05.0 per cent, however the preferable value is 3.5 per cent to control the autoclave expansion of the cement under the prescribed value of BIS. In IS 269:2015 the limit of MgO in case OPC 33, OPC 43 & OPC 53 is 6 per cent however in case of sleeper grade 43 & 53 it is 5 per cent. As a result the production of Porland cement become more stringent from the high MgO limestone.
During the pyroprossing around 02.0% MgO will dissolve in the clinker liquid predominantly in C4AF and contribute the liquid phase in rotary kiln. That is why some times change in MgO content of kiln feed can cause ball or coating ring formation. Above 2 per cent MgO remain as solid phase as Periclase. Due to slow hydration of the periclase mineral present in the cement makes its unsound. When the MgO is more than 2 per cent the rapid heating and cooling is beneficial for development of small periclase crystals in the clinker. These reactive periclase crystals are hydrated faster than the cement hardening. Therefore this do not cause any unsound by later expansion.
The hard burnt MgO in cement reacts with H2O very slowly to form Mg(OH)2 that causes volume expansion of 118 per cent. This volume expansion is after the cement is hardening thus makes the cement unsound and causes cracks in concrete. The higher MgO in cement retards the initial hydration of the cement and increase the setting time. During the hydration of the cement the solubility product Mg(OH)2 is much smaller than Ca(OH)2, hence the Mg(OH)2 precipitated earlier than Ca(OH)2 . The formation of Mg(OH)2 reduces the Ca(OH)2 saturation ratio, thus delaying the initiation of maximum of Ca(OH)2 saturation ratio. When MgO hydrate in high alkali medium the Mg(OH)2 with tiny crystals precipitates around the cement grains to forming a protective layer, hence retarding further hydration of the cement grains. MgO also gives some darker colour to the clinker. Measure to control MgO
The causes of the cement expansion by the crystalline MgO ( periclase) may be due to the following factors ( Dreizer 1981)
i. MgO Content in Raw Materials
ii. Chemical & Mineralogical composition of raw materials
iii. Raw meal preparation and fineness
iv. Pyroprocessing of the Cement Clinker
v. Size and distribution of the periclase in the cement
vi. Cement Fineness
vii. Cement Storage
viii. Cement Additives
Screening the limestone during crushing and blending with low MgO Limestone some times reduced the over all content of MgO in raw material. Grinding the raw meal finer for better burning. It has been observed that quartz and dolomites are weekly magnetic with relative attractivity of 0.37 and 0.22 respectively, where as the calcite is nonmagnetic with relative attractivity of 0.03. Hence, with high magnetic separator the silica and dolomite can be effectively separated from limestone. In case of electrostatic separation, it is not effective to separate the calcite and silica as they are having almost same relative empirical conductivity (voltage-10,920).

Whereas the relative empirical conductivity of Dolomite (voltage-8,268) is much lower than the calcite and quartz, as a result the dolomite crystals can be effectively separated from limestone by electrostatic separation methods.
The magnesia content more than 5 per cent is undesirable in cement grade limestone as it produce unsound cement. In most of the cases it has been found that the dolomitization in limestone alter the calcite in such a way that magnesia limestone nearly defies any economic separation. However, removal of dolomite crystals from limestone is possible through air cyclone effectively. A detailed study on establishment of cost effective beneficiation technique for separation of dolomite (MgO) from limestone is essential.
A study of clinker cooling reveals that under slow cooling, only 1.5 per cent of MgO is retained in solid solution and rest crystallized as larger periclase crystals and makes the cement unsound. The rapid cooled clinker forms smaller alite and belite crystals, exhibits faster strength growth during hydration, and is able to accommodate the hydration of periclase (MgO) considerably. Various studies say that increasing the fineness of cement and addition of fly ash effectively stabilises MgO up to 10 per cent in Portland cements.
With the lower Lime Saturation Factor (LSF) (0.94to 0.97) the high MgO in raw meal does not have any influence on the free lime generation during pyro-processing. Whereas incase of high LSF (0.97-1.00) any increase of MgO in raw meal result more free lime generation and results unsound cement.
The free MgO decrease in cement clinker as the iron content in the raw meal increase. It has been observed that a cement containing 5.0 per cent MgO and 2.3 per cent Fe2O3 had the autoclave expansion of 1.28 per cent whereas another cement containing 4.95 per cent MgO and 3.6 per cent Fe2O3 exhibit the autoclave expansion of 0.15 per cent. The iron content in the raw meal should in the following ratio to control the autoclave expansion.
Fe2O3 = 2+ (0.2xMgO).
Further the ratio between (Alumina +MgO)/Fe2O3should be maximum 2.7 for production of sound cement. When the MgO: Fe2O3 >1.53 the autoclave expansion of the cement is in danger zone. When the ratio of MgO: Fe2O3 < 1.40 probability of expansion failure decrease rapidly and MgO: Fe2O3 < 1.20 is the limiting value for production sound cement.
During pyroprocessing the C4AF is act as an excellent stabilizer for MgO and capable of transforming the considerable amount of MgO into nun expanding compounds. The autoclave expansion due to MgO may be control by lowering the alumina modulus of the raw meal. This will enhance the C4AF content in cement and less C3 A. The C3A should maintain 6-8 per cent in the cement clinker to control the MgO in form expansion. The higher MgO content in raw meal consumes extra thermal energy also.
In case of hard burning even the raw meal having 2.5 per cent MgO fails in autoclave expansion. Whereas the light burning raw meal containing 5 per cent MgO does not fail in autoclave expansion as it hydrates rapidly before the cement sets.
The higher SO3 in the Portland cement clinker also prevented the autoclave expansion in case of high MgO limestone. it has been observed that in case of 5 per cent MgO containing clinker if the SO3 is 2.17 per cent the autoclave expansion is 0.44 per cent. When the SO3 content in the cement decreased to 1.01 per cent the autoclave expansion increase to 4 per cent. From the above it can be concluded that in case of high MgO limestone the petcoke with high sulfur is suitable. It has been reported that the use of 0.4-0.8 per cent fluorspar (CaF2) in raw mix as mineralizer reduced the size of periclase to 1-7 micron in the cement clinker.
By the fast cooling of the clinker, the MgO retained in the solution in the glass form. This reduce the expansion of the cement due to periclase. On the other hand in case of the slow cooling clinker the more periclase (MgO) crystallized out of the melt and larger crystals were formed . These large crystals of MgO are responsible for the failure of autoclave expansion of the cement.
The smaller size of periclase crystals in the cement does not contribute to autoclave expansion as the smaller periclase crystals are predominantly located in the interstitial phases. In an experiment it has been observed that cement clinker containing 6.5 per cent (5.4 per cent free periclase) MgO ground with 2 per cent SO3 containing and free lime (CaO) of 0.47 per cent. When the particle size distribution of this cement is 80 per cent of the periclase is <5.0 micron size and 20 per cent periclase is size of 5.0-15.0 micron the autoclave expansion of the same cement found only 0.47 per cent.
Coarser the ground of the cement have always exhibited a greater amount of the autoclave expansion in case of clinker having high MgO content. Therefore, incase of high MgO clinker the cement should be ground finer to control expansion. It has been observed when a high MgO content clinker ground to 225 m2/kg was showed the autoclave expansion of 7.06 per cent. When the fineness of the same cement enhanced to 350 m2/kg the autoclave expansion dropped to 1.49 per cent. With the increase of fineness of the cement to 400 m2/kg the autoclave reduced to 0.24 per cent.
Longer the curing of cement concrete decreases the autoclave expansion considerably. In an experiment it has been observed that the autoclave expansion of a cement containing 5 per cent MgO and 0.22 per cent free lime in case of 3 days curing cement concrete is 0.48 per cent and expansion of the same cement in 7 days curing reduced to 0.22 per cent. Alternate for production of cement
The production of the blended cement or composite cement are the best alternative for cement production in case of high MgO clinker mix in stead of ordinary Portland cement. In case of the Portland slag cement and composite cement the limit of MgO in cement has been enhanced to 8 per cent. The unsoundness of the cement can deduced by adding 60-70 per cent GGBFS or fly ash 15-30 per cent in OPC. The higher content of MgO even 5-15 per cent can be tolerated with the addition of the above pozzolanaic materials. Hydration of high MgO cement under autoclave conditions cause rapid formation and crystallization of Mg(OH)2 creation of larger pore sizes. This result in loss of mechanical strength and higher expansion value.
Under the ambient water curing precipitation and distribution of C-S-H gel into finer net work causes a homogeneous morphology and development of smaller pores. The resultant higher mechanical strength associated with partial hydration of MgO yields reduced expansion. High MgO cement paste containing fly ash also showed considerable pore refinement and improved hydrate morphology favouring volume stability under both autoclave and embient water curing.
In recent years, Sufoalluminate Belite cements receiving a lot of interest, as it can be manufacture from various industrial wastes and low grade limestone, environment friendly and requires less thermal energy for manufacture than the Portland clinker.
Raw mixes for C4A3S clinker differ from the Portland cement as they contain significant amount of sulphate. Therefore, the reactions and product are quite different from those normally found in Portland cement production. The total lime requirement for production of such cement is less than 50 wt% as against the about 65 wt% for Portland cement. This indicates that for production of Sufoalluminate Belite cement the low grade limestone are also suitable. The Sulfoaluminate Belite clinker can be produced by burning limestone, bauxite and gypsum at around 12000C. For production of Sufoalluminate Belite cement the Lime Saturation Factor (LSF) requirement is low around 0.67, which reduces the consumption of limestone stone in manufacture.
As the consumption of lime is less, for manufacture of this type of cement it generates around 35 per cent less CO2 than the Portland cement. The requirement of thermal energy in production of Sufoalluminate Belite cement is also much less than the Portland cement as it is manufactured at 12000C. It has been found that the Sufoalluminate Belite is having very good dimensional stability, sulfate resistance, compressive strength development and better resistance to atmospheric carbonation comparable to commercial Portland cement. Presently these cements are produced commercially some of the countries such as China, Japan, Russia successfully. These cements are best suitable for the construction in the coastal areas owing to their sulphate resistance property.
The Sulfoaluminates Belite Cement contains C4A3S as main component together with Calcium Sulfate, Dicalcium Silicate (C2S), Tetracalcium Iron Aluminate (C4AF), Calcium Sulfosilicate (C3S2F), Calcium Aluminate (C3A,CA,&C12A7) and Silicoaluminates (C2AS, CAS3). The mineralogical composition of the Sufoalluminate Belite cement are quite different than the Portland cement ( Table -2) as it contains relatively high concentration of C2S, C4A3S and C4AF. Thus these cements shows different properties during the hydration and capability to control periclase effect during hydration to make sound cement.
The Sufoalluminate Belite is chemically different markedly from the Portland Cement. The rapid setting of sulfoaluminate cement is mainly due to quick conversion of C4A3S to hydration product during early age hydration. On hydration the gypsum react with C4A3S and from ettringite (C6AS3H32) to regulate the technical properties of Sulfoaluminate Belite cements.
4 CaO3Al2O3SO3+8CaSO4+6CaO+93H2O ? 3 (CaOAl2O3CaSO431H2O)
The formation of the ettringite is very fast in this case, as a result in reduced workability of the cement and required retarder. The C2S present in this cement add the strength and durability. The mortars of such cements also has comparable compressive strength and total porosity when compared with Portland Cement. The mortar prepared from the Sufoalluminate Belite cement release less quantity of Ca(OH)2 than the Portland cement mortar on hydration, thus reduces the porosity of the concrete.
The higher content of gypsum in the Sufoalluminate Belite cement also decrease the carbonation of concrete. The Sufoalluminate Belite cement exhibits better protection for the steel reinforcement corrosion. Presently these cements are produced commercially some of the countries such as China, Japan, Russia successfully. These cements are best suitable for the construction in the coastal areas owing to their sulphate resistance property.
The influence of MgO on the composition structure and properties of alite calcium strontium sulphoaluminate cement were investigated. The results show that when the mass fraction of MgO is 1-5 per cent the early strength of cement can be enhanced significantly. The optimal content of MgO in cement clinker is 2 per cent and the compressive strength of the cement at 3, 28 days are 64.3 and 103.6 MPa respectively.
The suitable amount of MgO can promote the formation of cl.5Sr2 S A3, while the formation of cl.5Sr2 S A3 can be hindered if the content of MgO is excessive. The existence of MgO can improve the formation of C3S, increasing the mechanical properties of the cement. Compared to Portland cement the Calcium Strontium Sulphoaluminate cement has higher capacity to dissolve MgO which indicate that the low quality high magnesium limestone can be effectively used in cement production.Conclusion
From the above analysis it can be concluded that fort use of high MgO limestone in Cement production the following measures can be taken.
Screening of dolomitic limestone and blending with low MgO limestone to control the MgO in the Raw meal . It should not be more than 5 per cent limestone.

The raw meal should the finer for the better reactivity in pyroprocessing
The Lime Saturation factor and Alumina Modulus should be low incase of high MgO Raw Mixes. Lowering the C3A and increasing C4AF contents could readily counteract the autoclave expansion due to high MgO content in cement
Maintaining the (Al2O3+MgO)/ Fe2O3 in the raw meal <1.2 control the formation of periclase in clinker
Use of CaF2 and Gypsum as mineralizer reduces considerably the formation of larger size pericalse crystals, thus control the expansion of the cement
The rapid cooling of Portland clinker causes the MgO in the solution in the glass form and reduced autoclave expansion
The cement ground finer more than 400 m2/kg reduced the autoclave expansion
The longer days of curing the cement concrete the autoclave expansion decrease considerably
Production of blended cement and composite cement the MgO contentment up to 10 per cent in cement can be adjusted for production of sound cement
The sulpho aluminate cement can be produced from the high MgO limestone may be the one of the alternative to use these materials

Acknowledgement
The authors are thankful to AKS University, Satna management for providing all the support and permission to publish this paper.
References
1. Role of Miner Elements in Cement Manufacture and Use: Javed I Bhatty, Portland Cement A, Association: PCA R&D Serial No. 1990.
2. Utilization of Low Grade Limestone in Cement Manufacture: An Indian Prospective : G C Mishra, Neerja Shukla, Anant Kumar Soni : 14th International Seminar on Cement and Building materials : New Delhi :2014
3. Volume Stabilization of High MgO cement : Effect of curing condition and fly ash addition: M M Ali and AK Malik: National Council for Cement and Building Materials: New Delhi: Cement & Concrete Research Volume 28: No 11, PP 1585-1594: 1998.
4. Reports of the Working Group on Cement Industry for XII Five Year Plan: Department of Industrial Policy and Promotion, Ministry of Commerce and Industry , Govt of India December 2011.
5. Performance of Sulfoaluminate-Belite Cement with High C4A3S Content: Ivan Janotka, L’udovit Krajci, Subhash C Manjumdar : Ceramic ?Silikaty 31 (2) 74-81 (2007).
6. Synthesis of Calcium Sulfoaluminate Cements from Al2O3-Rich by products from Aluminium Manufacture: Milena Marro, Maria Lucia Pace, Anotonio Telesica and Gian Lorenzo Valenti: Second International Conference on Sustainable Construction Materials and Technologies: 28-30 June, 2010 Universita Politecnica della Marche, Ancona, Italy.
7. Beneficiation studies of the Limestone of Malkhed Areas, Gulbarga District, Karnantaka: Chinnaiah, Sunil Kumar R K, Basavarajappa H T and Madesh P. International Journal of Earth Science and Engineering: Volume 05, No.01 : February 2012: pp 186-192.
8. Hydrating Behaviour of Activated Belite Sulfoaluminate Cements: Aranda, M A G., Cuberos, A J M., Cuesta A., Alvarez-Pinazo, De la , A G.
9. Beneficiation studies on low grade limestone of Shahabad Araea, Shahabad, Gulbarga District, Karnantaka: MR Patil and M V Rudramuniyappa: Proceedings of the XI International Seminar on Mineral Processing Technology (MPT-2010): pp 725-729.Prof GC Mishra is Director, AKS University, Satna, and former Additional Director National Council for Cement and Building Materials. He has more than 36 years experience in cement and concrete. Dr KN Bhattacharjee is Professor from
The Department of Cement Technology, AKS University, Satna, and former General Manager of Lafarge Cement. He has over 35 years experience in cement and concrete.

Economy & Market

Impactful Branding

Published

1 year ago

July 17, 2023

admin

Advertising or branding is never about driving sales. It’s about creating brand awareness and recall. It’s about conveying the core values of your brand to your consumers. In this context, why is branding important for cement companies? As far as the customers are concerned cement is simply cement. It is precisely for this reason that branding, marketing and advertising of cement becomes crucial. Since the customer is unable to differentiate between the shades of grey, the onus of creating this awareness is carried by the brands. That explains the heavy marketing budgets, celebrity-centric commercials, emotion-invoking taglines and campaigns enunciating the many benefits of their offerings.
Marketing strategies of cement companies have undergone gradual transformation owing to the change in consumer behaviour. While TV commercials are high on humour and emotions to establish a fast connect with the customer, social media campaigns are focussed more on capturing the consumer’s attention in an over-crowded virtual world. Branding for cement companies has become a holistic growth strategy with quantifiable results. This has made brands opt for a mix package of traditional and new-age tools, such as social media. However, the hero of every marketing communication is the message, which encapsulates the unique selling points of the product. That after all is crux of the matter here.
While cement companies are effectively using marketing tools to reach out to the consumers, they need to strengthen the four Cs of the branding process – Consumer, Cost, Communication and Convenience. Putting up the right message, at the right time and at the right place for the right kind of customer demographic is of utmost importance in the long run. It is precisely for this reason that regional players are likely to have an upper hand as they rely on local language and cultural references to drive home the point. But modern marketing and branding domain is exponentially growing and it would be an interesting exercise to tabulate and analyse its impact on branding for cement.

Concrete

Indian cement industry is well known for its energy and natural resource efficiency

Published

2 years ago

November 18, 2022

admin

Dr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL) takes us through the multifaceted efforts that the company has undertaken to keep emissions in check with the use of alternative sources of energy and carbon capture technology.

Tell us about the policies of your organisation for the betterment of the environment.
Caring for people is one of the core values of our JK Lakshmi Cement Limited. We strongly believe that we all together can make a difference. In all our units, we have taken measures to reduce carbon footprint, emissions and minimise the use of natural resources. Climate change and sustainable development are major global concerns. As a responsible corporate, we are committed with and doing consistent effort small or big to preserve and enrich the environment in and around our area of operations.
As far as environmental policies are concerned, we are committed to comply with all applicable laws, standards and regulations of regulatory bodies pertaining to the environment. We are consistently making efforts to integrate the environmental concerns into the mainstream of the operations. We are giving thrust upon natural resource conservation like limestone, gypsum, water and energy. We are utilising different kinds of alternative fuels and raw materials. Awareness among the employees and local people on environmental concerns is an integral part of our company. We are adopting best environmental practices aligned with sustainable development goals.
Udaipur Cement Works Limited is a subsidiary of the JK Lakshmi Cement Limited. Since its inception, the company is committed towards boosting sustainability through adopting the latest art of technology designs, resource efficient equipment and various in-house innovations. We are giving thrust upon renewable and clean energy sources for our cement manufacturing. Solar Power and Waste Heat Recovery based power are our key ingredients for total power mix.

What impact does cement production have on the environment? Elaborate the major areas affected.
The major environmental concern areas during cement production are air emissions through point and nonpoint sources due to plant operation and emissions from mining operation, from material transport, carbon emissions through process, transit, noise pollution, vibration during mining, natural resource depletion, loss of biodiversity and change in landscape.
India is the second largest cement producer in the world. The Indian cement industry is well known for its energy and natural resource efficiency worldwide. The Indian cement industry is a frontrunner for implementing significant technology measures to ensure a greener future.
The cement industry is an energy intensive and significant contributor to climate change. Cement production contributes greenhouse gases directly and indirectly into the atmosphere through calcination and use of fossil fuels in an energy form. The industry believes in a circular economy by utilising alternative fuels for making cement. Cement companies are focusing on major areas of energy efficiency by adoption of technology measures, clinker substitution by alternative raw material for cement making, alternative fuels and green and clean energy resources. These all efforts are being done towards environment protection and sustainable future.
Nowadays, almost all cement units have a dry manufacturing process for cement production, only a few exceptions where wet manufacturing processes are in operation. In the dry manufacturing process, water is used only for the purpose of machinery cooling, which is recirculated in a closed loop, thus, no polluted water is generated during the dry manufacturing process.
We should also accept the fact that modern life is impossible without cement. However, through state-of-the-art technology and innovations, it is possible to mitigate all kinds of pollution without harm to the environment and human beings.

Tell us about the impact blended cement creates on the environment and emission rate.
Our country started cement production in 1914. However, it was introduced in the year 1904 at a small scale, earlier. Initially, the manufacturing of cement was only for Ordinary Portland Cement (OPC). In the 1980s, the production of blended cement was introduced by replacing fly ash and blast furnace slag. The production of blended cement increased in the growth period and crossed the 50 per cent in the year 2004.
The manufacturing of blended cement results in substantial savings in the thermal and electrical energy consumption as well as saving of natural resources. The overall consumption of raw materials, fossil fuel such as coal, efficient burning and state-of-the-art technology in cement plants have resulted in the gradual reduction of emission of carbon dioxide (CO2). Later, the production of blended cement was increased in manifolds.
If we think about the growth of blended cement in the past few decades, we can understand how much quantity of , (fly ash and slag) consumed and saved natural resources like limestone and fossil fuel, which were anyhow disposed of and harmed the environment. This is the reason it is called green cement. Reduction in the clinker to cement ratio has the second highest emission reduction potential i.e., 37 per cent. The low carbon roadmap for cement industries can be achieved from blended cement. Portland Pozzolana Cement (PPC), Portland Slag Cement (PSC) and Composite Cement are already approved by the National Agency BIS.
As far as kilogram CO2 per ton of cement emission concerns, Portland Slag Cement (PSC) has a larger potential, other than PPC, Composite Cement etc. for carbon emission reduction. BIS approved 60 per cent slag and 35 per cent clinker in composition of PSC. Thus, clinker per centage is quite less in PSC composition compared to other blended cement. The manufacturing of blended cement directly reduces thermal and process emissions, which contribute high in overall emissions from the cement industry, and this cannot be addressed through adoption of energy efficiency measures.
In the coming times, the cement industry must relook for other blended cement options to achieve a low carbon emissions road map. In near future, availability of fly ash and slag in terms of quality and quantity will be reduced due to various government schemes for low carbon initiatives viz. enhance renewable energy sources, waste to energy plants etc.
Further, it is required to increase awareness among consumers, like individual home builders or large infrastructure projects, to adopt greener alternatives viz. PPC and PSC for more sustainable
resource utilisation.

What are the decarbonising efforts taken by your organisation?
India is the world’s second largest cement producer. Rapid growth of big infrastructure, low-cost housing (Pradhan Mantri Awas Yojna), smart cities project and urbanisation will create cement demand in future. Being an energy intensive industry, we are also focusing upon alternative and renewable energy sources for long-term sustainable business growth for cement production.
Presently, our focus is to improve efficiency of zero carbon electricity generation technology such as waste heat recovery power through process optimisation and by adopting technological innovations in WHR power systems. We are also increasing our capacity for WHR based power and solar power in the near future. Right now, we are sourcing about 50 per cent of our power requirement from clean and renewable energy sources i.e., zero carbon electricity generation technology. Usage of alternative fuel during co-processing in the cement manufacturing process is a viable and sustainable option. In our unit, we are utilising alternative raw material and fuel for reducing carbon emissions. We are also looking forward to green logistics for our product transport in nearby areas.
By reducing clinker – cement ratio, increasing production of PPC and PSC cement, utilisation of alternative raw materials like synthetic gypsum/chemical gypsum, Jarosite generated from other process industries, we can reduce carbon emissions from cement manufacturing process. Further, we are looking forward to generating onsite fossil free electricity generation facilities by increasing the capacity of WHR based power and ground mounted solar energy plants.
We can say energy is the prime requirement of the cement industry and renewable energy is one of the major sources, which provides an opportunity to make a clean, safe and infinite source of power which is affordable for the cement industry.

What are the current programmes run by your organisation for re-building the environment and reducing pollution?
We are working in different ways for environmental aspects. As I said, we strongly believe that we all together can make a difference. We focus on every environmental aspect directly / indirectly related to our operation and surroundings.
If we talk about air pollution in operation, every section of the operational unit is well equipped with state-of-the-art technology-based air pollution control equipment (BagHouse and ESP) to mitigate the dust pollution beyond the compliance standard. We use high class standard PTFE glass fibre filter bags in our bag houses. UCWL has installed the DeNOx system (SNCR) for abatement of NOx pollution within norms. The company has installed a 6 MW capacity Waste Heat Recovery based power plant that utilises waste heat of kiln i.e., green and clean energy source. Also, installed a 14.6 MW capacity solar power system in the form of a renewable energy source.
All material transfer points are equipped with a dust extraction system. Material is stored under a covered shed to avoid secondary fugitive dust emission sources. Finished product is stored in silos. Water spraying system are mounted with material handling point. Road vacuum sweeping machine deployed for housekeeping of paved area.
In mining, have deployed wet drill machine for drilling bore holes. Controlled blasting is carried out with optimum charge using Air Decking Technique with wooden spacers and non-electric detonator (NONEL) for control of noise, fly rock, vibration, and dust emission. No secondary blasting is being done. The boulders are broken by hydraulic rock breaker. Moreover, instead of road transport, we installed Overland Belt Conveying system for crushed limestone transport from mine lease area to cement plant. Thus omit an insignificant amount of greenhouse gas emissions due to material transport, which is otherwise emitted from combustion of fossil fuel in the transport system. All point emission sources (stacks) are well equipped with online continuous emission monitoring system (OCEMS) for measuring parameters like PM, SO2 and NOx for 24×7. OCEMS data are interfaced with SPCB and CPCB servers.
The company has done considerable work upon water conservation and certified at 2.76 times water positive. We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24×7. All digital metres and level recorders are monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. Effluent Treatment Plant (ETP) installed for mine’s workshop. Treated water is reused in washing activity. The unit maintains Zero Liquid Discharge (ZLD).
Our unit has done extensive plantations of native and pollution tolerant species in industrial premises and mine lease areas. Moreover, we are not confined to our industrial boundary for plantation. We organised seedling distribution camps in our surrounding areas. We involve our stakeholders, too, for our plantation drive. UCWL has also extended its services under Corporate Social Responsibility for betterment of the environment in its surrounding. We conduct awareness programs for employees and stakeholders. We have banned Single Use Plastic (SUP) in our premises. In our industrial township, we have implemented a solid waste management system for our all households, guest house and bachelor hostel. A complete process of segregated waste (dry and wet) door to door collection systems is well established.

Tell us about the efforts taken by your organisation to better the environment in and around the manufacturing unit.
UCWL has invested capital in various environmental management and protection projects like installed DeNOx (SNCR) system, strengthening green belt development in and out of industrial premises, installed high class pollution control equipment, ground-mounted solar power plant etc.
The company has taken up various energy conservation projects like, installed VFD to reduce power consumption, improve efficiency of WHR power generation by installing additional economiser tubes and AI-based process optimisation systems. Further, we are going to increase WHR power generation capacity under our upcoming expansion project. UCWL promotes rainwater harvesting for augmentation of the ground water resource. Various scientifically based WHR structures are installed in plant premises and mine lease areas. About 80 per cent of present water requirement is being fulfilled by harvested rainwater sourced from Mine’s Pit. We are also looking forward towards green transport (CNG/LNG based), which will drastically reduce carbon footprint.
We are proud to say that JK Lakshmi Cement Limited has a strong leadership and vision for developing an eco-conscious and sustainable role model of our cement business. The company was a pioneer among cement industries of India, which had installed the DeNOx (SNCR) system in its cement plant.

Concrete

NTPC selects Carbon Clean and Green Power for carbon capture facility

Published

2 years ago

October 12, 2022

admin

Carbon Clean and Green Power International Pvt. Ltd has been chosen by NTPC Energy Technology Research Alliance (NETRA) to establish the carbon capture facility at NTPC Vindhyachal. This facility, which will use a modified tertiary amine to absorb CO2 from the power plant’s flue gas, is intended to capture 20 tonnes of CO2) per day. A catalytic hydrogenation method will eventually be used to mix the CO2 with hydrogen to create 10 tonnes of methanol each day. For NTPC, capturing CO2 from coal-fired power plant flue gas and turning it into methanol is a key area that has the potential to open up new business prospects and revenue streams.