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Analysis of Trace Hazardous Elements and Halogens in Cement

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With more and more use of alternate raw materials and fuels, it is becoming essential to monitor the trace elements in the final product and also in the finished goods produced using cement. X-Ray analysis is one such full proof method to analyse and detect the trace elements.

The role of the cement industry for effective utilization of waste materials and by-products has been growing. Slag from steel plant and coal fly ash from thermal power plant are typical by-products. Waste tyers, plastics and sludge are common waste materials. In addition, waste materials such as incinerated ashes of household waste and sewage sludge are also utilized. These waste materials and by-products are added as a part of raw material for cement production.

The rate of using the materials for cement production has increased over the years for environmental protection and effective utilization of resources.

Addition of waste materials and by-products can increase the contents of hazardous heavy elements in cement product and, therefore, can cause pollution of the hazardous heavy elements eluted from concrete. Accordingly, control of hazardous elements is essential for cement plant operation.

On the other hand, chlorine creates problem in kilns and also causes corrosion of rebar (reinforcing steel) in concrete while fluorine affects hydration reaction. These trace halogens are other important elements to be analyzed.

X-ray fluorescence spectrometry is widely used for chemical composition analysis of major components such as CaO, SiO2, Al2O3 and Fe2O3 of raw materials, raw meal, clinker and cement in each production process for process control owing to a rapid and precise analytical method. In recent cement production, the demand for analyzing trace hazardous heavy elements and halogens has increased for environmental protection and effective utilization of resources. Since the number of trace elements to be analyzed is increasing, high power wavelength dispersive XRF spectrometers, which have good sensitivity and spectral resolution for both heavy and light elements down to fluorine, are suitable for such applications.

The analysis of trace heavy elements in cement using unique correction methods was evaluated and accurate results were obtained.

Analysis examples of trace heavy elements and halogens in cement using a high-power wavelength-dispersive XRF spectrometer are presented.

Analysis results
In order to demonstrate that the ZSX PrimusIII+ meets the requirement of ASTM C114-11, a qualification test in ASTM C114-11 was carried out using NIST CRM?s of cement. The test results are shown in Table 1, which proves that the spectrometer meets the requirement. Refer to Table 1

For chlorine and heavy trace elements in cement, calibration curves were generated with cement reference materials. The calibration results are summarized in Table 2 and representative calibration curves are shown in Figure 1.

For Cl, Cr, and Ba, alpha correction (?alpha? in Table 2), where correction coefficients for absorption and enhancement by co-existing element are calculated theoretically by the fundamental parameter method, was applied.

For Co, Cu, Zn, As, Sr, Zr, Mo, and Pb, scatter ratio correction (?scatter ratio? in Table 2), where a scatter line, Rh-Ka Compton or background, is used as internal standard line, was applied. This correction also minimizes analysis error caused by variation in grain size or mineral composition for powder samples.

For V and Ni, the combination of the scatter ratio and alpha corrections (?scatter ratio + alpha? in Table 2) was applied. In this unique correction method, when theoretical alphas are calculated by the fundamental parameter method, scatter lines are also considered in the calculation to obtain theoretical alphas for calibration with scatter ratio method applied. Additionally, for V, Ni, As, and Zr, spectral overlap correction was applied.

Conclusion
The qualification test for ASTM C114-11 was demonstrated by the pressed powder method using a high-power sequential WD-XRF spectrometer. Using this spectrometer, calibration curves were generated with inter-element correction methods for trace elements in cement, including chlorine and hazardous elements of Cr, As, and Cd. Then, good accuracy was obtained for each element.

The analysis results show that trace elements in cement can be analyzed with high accuracy on high-power sequential WD-XRF spectrometers.

*In the columns of ?Result?, only the maximum values among the analysis results of the seven NIST CRMs are listed.
**The maximum difference for Cl is 0.005 mass%, which exceeds the limit 0.003 mass% while the differences of all the other CRMs are less than 0.003 mass%. The value 0.005 mass% is less than the double of the limit, 0.006 mass%.
***No value is given.
*Correction: each method is explained below
The accuracy of calibration is calculated by the following formula,
Importance of analysing halogens and hazardous elements in cement
Use of waste materials and by-products has increased substantially in cement production
Control of hazardous heavy elements and chlorides in finished cement and then in concrete is essential
Presence of halogens creates problem in manufacturing process as well as in concrete which promotes corrosion of re-bars
Demand for analysing hazardous heavy elements and halogens is warranted for environment protection
Presence of Co, Cu, Zn, Sr, Zr, Mo, V, Ni, Cr, As, Cd and halogens can be detected accurately by RigakuZSX Primus III + or equivalent XRF machine
The standard in reference is ASTM C114-II

Article by Hisashi Inoue, Yasujiro Yamada & Yoshiyuki Kataoka of Rigaku Corporation, Osaka, Japan In India Rigaku is represented through I R Technology Services Pvt.Ltd, Navi Mumbai.

Contact: N L Deshpande- Chief General Manager

Table 1. Qualification test result

Analyte Analyte Calibration range Difference between duplicates Difference of the average ofduplicate
from the certificate values
Limit Result* Limit Result*
SiO2 18.637 ? 22.38 0.16 0.10 0.2 0.2
Al2O3 3.85 ? 7.06 0.20 0.04 0.2 0.1
Fe2O3 0.152 ? 3.09 0.10 0.003 0.10 0.04
CaO 57.58 ? 67.87 0.20 0.12 0.3 0.1
MgO 0.814 ? 4.475 0.16 0.04 0.2 0.1
SO3 2.086 ? 4.622 0.10 0.05 0.1 0.1
Na2O 0.021 ? 1.068 0.03 0.02 0.05 0.01
K2O 0.093 ? 1.228 0.03 0.003 0.05 0.01
TiO2 0.084 ? 0.366 0.02 0.01 0.03 0.01
P2O5 0.022 ? 0.306 0.03 0.01 0.03 0.004
ZnO 0.001 ? 0.107 0.03 0.001 0.03 0.002
Mn2O3 0.007 ? 0.259 0.03 0.001 0.03 0.002
Cl 0.0019 ? 0.013 0.003 0.005** N/A*** 0.006

Table 2. Calibration summary of trace elements in cement

Analyte Concentration range Accuracy Correction*
Cl 6 ? 84 2.6 alpha
V 28 ? 229 4.5 scatter ratio + alpha, overlap (Ti)
Cr 42.2 ? 225 1.7 alpha
Co 4.9 ? 41.3 1.3 scatter ratio
Ni 5.6 ? 74.6 1.7 scatter ratio + alpha, overlap (Co)
Cu 8.7 ? 203 5.5 scatter ratio
Zn 209 ? 1112 18 scatter ratio
As 1.9 ? 20.4 1.3 scatter ratio, overlap (Pb)
Sr 196 ? 573 15 scatter ratio
Zr 42 ? 142 2.3 scatter ratio, overlap (Sr)
Mo 3.5 ? 99.5 1.5 scatter ratio
Ba 130 ? 662 25 alpha
Pb 12.8 ? 435 2.0 scatter ratio

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Economy & Market

Impactful Branding

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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.

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Concrete

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

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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.

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Concrete

NTPC selects Carbon Clean and Green Power for carbon capture facility

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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.

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