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Gypsum, the speed breaker

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Gypsum is the most essential ingredient of the finished cement. Though useful, handling of gypsum in a cement plant is not so easy since it is a hygroscopic material and very sticky in nature.

The terms cement and concrete are used interchangeably, although cement is actually an ingredient of concrete; gypsum is often added to cement to slow down the setting (hardens) time. Cement sets quickly and retarding that process allows workers to pour the mixture into the various forms or frames needed.

The majority of cement plants in Greece mainly use natural gypsum to prevent rapid cement setting. The partial or total replacement of gypsum by materials, which contain calcium sulphate, has been instigated by two facts. Firstly, the increasing availability of low-cost by-products containing calcium sulphate and secondly, the prospect of the gypsum quarries to mine, in the near future, a rock that is a mixture of gypsum and anhydrite.

FGD gypsum, a waste material of the desulphurisation process in coal burning power plants, to convert SO3 content of flue gases into gypsum, is an important alternative source of chemical gypsum. The experiments done with only FGD gypsum shows that the setting time was influenced by the percentages of FGD gypsum addition in the mortars tested. The initial and final setting time increased with increasing FGD gypsum ratio. The compressive strength also was affected by increase of FGD gypsum in the mortars. At all ages the compressive strength of the mortar with addition of FGD gypsum in combination with natural gypsum was higher that to other mixtures. The performances of cements prepared with mixtures FGD gypsum/natural gypsum were better compared with that prepared only with natural gypsum. At the same time, a hydration study of cements with FGD is presented. The addition of FGD gypsum increases setting time without affecting the compressive strength profile. The degree of dehydration of the dehydrated calcium sulphate regulates setting and strength performance of the cement partially replaced with either anhydrite or FGD gypsum.

In addition, gypsum will react with the tricalcium aluminate mineral (C3A), which is the compound mainly responsible for the early setting time of cement. The reaction of gypsum with (C3A) will retard the setting time of cement (i.e. prolong the setting time), which is necessary for concreting operations to be completed perfectly, if the amount of gypsum is small the setting time will be short, however, addition large amount of gypsum to the clinker during its grinding will delay the harden of the cement paste and producing a large amount of heat during the reaction and solidification of concrete. Therefore the amount of gypsum should be controlled to achieve the proper setting time and decreasing the percentage of SO3 in the concrete, and to avoid steel corrosion and concrete structure deformation.

While producing 53 grade of cement, generally cement plant prefers to use mineral gypsum. Today industry faces shortage of mineral gypsum, which is the purer form of gypsum and the gap is bridged by synthetic gypsum mainly coming from fertiliser industry. This gypsum is commonly known as chemical gypsum. Shreesh Khadilkar in his article has covered in details about various options available on sourcing gypsum. As stated by Shreesh, FGD gypsum from thermal plants can become alternate source in place of fertiliser gypsum but it is still at an experimental stage.

Handling of gypsum in a cement plant is not so easy since it is a hygroscopic material and very sticky in nature. The readers now will appreciate that though gypsum is essential ingredient of cement but proving to be a speed breaker.

VIKAS DAMLE

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Economy & Market

Leonard Unveils Dual-Head Robotic Arm for Hazardous Industrial Demolition

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 Leonard unveils Descender Duo, a dual-head robotic demolition arm designed to improve industrial safety and reduce shutdown time by up to 50 per cent.

Industrial robotics and refractory services specialist Leonard has launched Descender Duo, a dual-head robotic demolition arm designed to improve safety, accelerate maintenance and reduce shutdown times in hazardous industrial environments. The system made its debut at Lisahally Power Station in Northern Ireland, removing 25 tonnes of slag material within hours.

Developed for the cement, metals, waste-to-energy and petrochemical industries, Descender Duo enables remote-controlled refractory demolition, anchor cutting and welding, and refractory spraying inside boilers, calciners and silos. Its vertical-access design eliminates the need for personnel to enter confined, high-risk spaces during these operations.

Weighing less than two tonnes, the pre-assembled system requires an access opening of just 1.2 m². Supported by an external overhead hoist, it uses electrically operated hydraulic stabilising legs to secure itself inside vessels. The robotic arm offers 360-degree rotation and is suited to vessels approximately 9 m in diameter, with its operating reach extendable through strategically positioned access points.

Equipped with two independently controlled robotic heads, Descender Duo can perform identical or different tasks simultaneously, including refractory demolition, anchor cutting and spraying. Its remote-control system incorporates live camera feeds, allowing operators to monitor operations without entering hazardous environments.

According to Leonard, the technology can deliver time savings of up to 50 per cent compared with manual methods. Its ability to operate at temperatures exceeding 100°C allows maintenance to begin as early as 24 hours after burner shutdown. An all-electric power supply further supports cleaner and more cost-efficient operations.

First Deployment Demonstrates Shutdown Efficiency

The system was first deployed at Burmeister & Wain Scandinavian Contractor’s (BWSC) Lisahally Power Station in Londonderry, Northern Ireland. The facility generates electricity from grade C waste wood, supplying approximately 40,000 homes and businesses.

Leonard and BWSC collaborated to develop a customised solution for the plant’s 26-metre furnace, where extensive external pipework created significant access challenges.

Mark Leonard, Managing Director, Leonard, said, “It required new thinking and rather than step away from the problem we were committed to solving it for the customer, with the customer. We’re relentless in our approach to tackling complex challenges, head-on. We took our years of cement plant experience, coupled with our working knowledge of the BWSC plant, and designed, engineered and tested a completely new vertical solution within just seven weeks from that initial conversation with the customer. That solution was the Descender Duo as we know it today.”

Traditionally, the furnace required a cooling period of up to 36 hours before preparatory work could begin, followed by manual slag removal using rope-access personnel. With Descender Duo, work commenced just 24 hours after shutdown, reducing downtime by up to one day.

The deployment removed 25 tonnes of slag within hours, eliminated the need for at least six workers to enter the hazardous furnace interior and saved 26 hours in the shutdown programme.

“The effectiveness exceeded expectation,” said Martin Doran, Plant Manager at Lisahally Power Station.

“When the Descender Duo concept was first discussed, we had to spend some time with the team from Leonard looking at how it was going to be moved into the furnace. Every site is different and that presented its own challenges, but nothing that the team couldn’t overcome. Once it was installed we were hugely impressed by its efficiency.”

Expanding Industrial Robotics Applications

Descender Duo joins Leonard’s existing portfolio of robotic maintenance solutions, including the Axis horizontal-access arm, Nano confined-space access arm, Charger cement mill media recharging system and Calibre cement mill media grading system.

Headquartered in Northern Ireland, Leonard provides robotic refractory demolition, installation, inspection and industrial maintenance services across the cement, metals, energy, biomass, glass and civil engineering sectors.

Formerly known as G Leonard, the company has more than 35 years of industry experience and operates across Europe, North America, the Middle East, Africa and Asia-Pacific.

The latest innovation reinforces Leonard’s focus on replacing hazardous manual processes with robotic systems that improve workforce safety, enhance operational efficiency and minimise industrial downtime.

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Concrete

Martin Engineering Appoints Ashwini Khunte as India General Manager

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Martin Engineering names Ashwini Khunte India General Manager to strengthen operations and drive growth across key bulk material handling sectors.

Pune

Martin Engineering, a global provider of bulk material handling solutions, has appointed Ashwini Khunte as General Manager of its India business, strengthening its leadership as the company expands its presence across the country’s cement, mining, steel, power and infrastructure sectors.

Khunte brings more than a decade of experience with Martin Engineering, having joined its Indian operations in 2013 as a Design Engineer, shortly after the company established its presence in the country in 2012.

A mechanical engineer by qualification, she spent her initial five years developing bulk material handling solutions in collaboration with the company’s operations team. During this period, she gained extensive experience addressing operational challenges in the steel, cement and coal industries. She subsequently moved into project engineering, managing major engineering, procurement and construction (EPC) and original equipment manufacturer (OEM) projects from initial enquiry to commissioning. Her responsibilities later expanded to overseeing Martin Engineering’s conveyor product portfolio in India, involving customer engagement, technical presentations and site visits across heavy industries.

In 2024, Khunte was promoted to Head of Sales & Marketing for the company’s Europe, Middle East, Africa and India (EMEAI) region. The position broadened her international market exposure and strengthened her strategic and commercial leadership capabilities.

Commenting on her appointment, Ashwini Khunte, General Manager, Martin Engineering India, said: “India represents a tremendous opportunity for Martin Engineering. The country’s continued investment in cement, mining, steel, power and infrastructure is creating increasing demand for safer, cleaner and more productive bulk material handling, and that’s exactly what we do. My priority will be to build on the strong foundations already established in India, while continuing to develop our people, strengthen customer relationships and bring practical solutions to the challenges faced by our industry.”

Robert Whetstone, Area Vice President – EMEAI, Martin Engineering, highlighted Khunte’s technical expertise, market understanding and leadership experience.

“Ashwini brings an exceptional combination of technical understanding, customer knowledge and commercial leadership. She has grown as Martin Engineering has grown, and has consistently demonstrated outstanding capability to transform her expertise into practical solutions. Her knowledge of the Indian market, together with her international experience, makes her ideally suited to lead our India business through its next stage of growth for years to come.”

Since establishing its Indian business in 2012, Martin Engineering has expanded its local workforce, manufacturing capabilities and dealership network. The company supplies conveyor products, transfer point solutions, material flow aids, training and technical support to bulk material handling industries. Khunte’s appointment positions the company to further strengthen customer relationships and expand its solutions portfolio in India’s growing industrial and infrastructure markets.

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Concrete

Fornnax Wins AIRIA’s Special Export Award for Rubber Machinery in 2025-26

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Fornnax Technology Pvt. Ltd. has been honoured with the Special Export Award – Rubber Machinery for 2025–26 by the All-India Rubber Industries Association (AIRIA), in recognition of its highest exports of tyre recycling plants to the European region.

With more than a decade of experience in India’s tyre recycling industry, Fornnax has contributed to the development of advanced recycling technologies and infrastructure. The company currently holds a 90% market share in India’s domestic tyre recycling sector, while exports account for 30% of its business, spanning markets such as Europe, Australia and the GCC.

The award marks another milestone for Fornnax, whose tyre recycling lines and advanced shredding technologies are supporting the growth of the circular economy in India and international markets.

Commenting on the recognition, Mr. Jignesh Kundaria, Founder and Director of Fornnax, said:

“This honour from AIRIA is a reflection of an incredible journey we have undertaken over the years. When we started Fornnax, there was no established recycling industry in India to follow. We chose to build for the future instead. Today, when you see India’s tyre recycling sector, it has already transformed into a dynamic, high-growth industry and we are extremely proud to have played our part in building it.”

Unlike standalone equipment suppliers, Fornnax focuses on developing complete, high-capacity recycling infrastructure. Its integrated systems combine multiple stages of shredding and size reduction to enable efficient, continuous operations. This system-level engineering approach helps recycling operators improve throughput, equipment reliability and operational consistency.

The recognition reinforces Fornnax’s commitment to developing engineering technologies that contribute to a more efficient and circular recycling ecosystem.

Looking ahead, the company aims to expand its international presence while continuing to develop advanced shredding and recycling solutions to address the growing volumes and evolving requirements of the global recycling industry.

For more information, visit: www.fornnax.com

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