Worldwide news on the topic of “Fly Ash and Coal Use” from 2017

India: Ambuja Cement has launched Ambuja Compocem, a composite cement made from fly ash and slag. The product is being produced at its Chhattisgarh plant and it has been introduced to markets in Bihar and Jharkland. It is being marketed to all market segments including individual house builders, real estate developers and infrastructure projects.

“With the launch of Ambuja Compocem, we have achieved a three pronged sustainability approach by conserving natural resources, creating a greener product and fulfilling customer needs for a superior performance product. We call this approach delivering true value,” said Ambuja Cement’s managing director and chief executive officer Ajay Kapur.

Taking into account the current specific consumption of coal per megawatt of electricity and the increasing trend of average ash content in coal rising up to, say, 40% in the near future, an additional 116 GW of installed capacity of coal-based thermal power by 2022—if ultimately realized as planned—may result in the generation of more than 400 MT of coal ash annually. If current modes and trends of ash use continue in the future, there would be an appalling accumulation of unused coal ash causing environmental pollution problems.

Technologically, the bridging of the gap cannot be attempted by developing niche application strategies. Success lies in achieving newer technological approaches for bulk use and in maximizing its use in cement, concrete, mine filling, and agriculture. The feasibility of such expansion in ash application sectors depends on the characteristics of Indian fly ash and the capability of the research community to manipulate its properties.

Israel: Over 20 years of collaboration between research teams in the United States and Europe in the fields of leaching, environmental assessment, and test standardization resulted in the joint-scheme Leaching Environmental Assessment Framework (LEAF). The framework recommends a collection of four leaching tests that follow the tiered approach of leach testing as published in literature (Kosson, et al. 2002; Kosson, et al. 2014) with applicability to a wide range of materials and uses.

A major achievement of LEAF was the extensive documentation of the technical basis (Garrabrants, et al. 2010) and interlaboratory validation process of four new U.S. Environmental Protection Agency (EPA) test methods that resulted in common practice characterization tests of wastes in general, and fly ash in particular (Garrabrants, et al. 2012a; Garrabrants, et al. 2012b). Analogous test methods are available in Europe through the European Committee for Standardization (CEN) for use in evaluation of waste, soil, sludge, and construction products (van der Sloot 2003; van der Sloot, et al. 2008).

The four leaching tests contained within LEAF comprise:

• Method 1313: Liquid-Solid Partitioning as a Function of Eluate pH Using a
• Parallel Batch Extraction Procedure (EN14429 or EN14997)
• Method 1314: Liquid-Solid Partitioning as a Function of Liquid-to-Solid Ratio
• Using an Up-Flow Percolation Column Procedure (EN14405)
• Method 1315: Mass Transfer Rates in Monolithic and Compacted Granular
• Materials Using a Semi-Dynamic Tank Leaching Procedure (EN15863)
• Method 1316: Liquid-Solid Partitioning as a Function of Liquid-to-Solid Ratio
• Using a Parallel Batch Extraction Procedure (partly EN12457-1 and 2)

LEAF includes the program LeachXS Lite™ for database management, enabling comparisons of leaching data for different tests or materials, including outputting data to Microsoft Excel®.

LeachXS Lite is available for free licensing and is based on the LeachXS™ platform. The full-featured software in LeachXS Pro allows for advanced modeling and data management capabilities beyond the features included in LeachXS Lite and is licensed for an annual fee. In the last several years, the Geological Survey of Israel (GSI) has been leading the incorporation of LEAF (data management and leaching test methods) into coal fly ash monitoring (Teutsch, et al. 2017) and research together with Professor David Kosson (Vanderbilt University) and Dr. Hans van der Sloot (van der Sloot Consultancy), who are among the development team of LEAF

Figure 1. Israeli coal fly ash use in 2017. Quantities of each type of application are presented in thousands of tons and in percentage of fly ash used.

 UAE: Renca, a technology start-up working with Dubai’s Future Accelerators programme, has developed a geopolymer cement from fly ash and ground granulated blast slag that can be used in 3D printing, according the National newspaper. The product’s advantage over Ordinary Portland Cement when used in additive manufacturing is that it can be used without additives making it cheaper. The start-up is a joint venture between Andrey Dudnikov, a Russian businessmen, and Alex Reggiani, an Italian geologist and mineralogist. The company is working with the Dubai Municipality to develop its material for use in 3D printing projects in Dubai. The company is also looking to set up a plant for its product in the city.

 Turkey: Turkey is one of the few countries that is actively planning to expand its coal-fueled power capacity relative to the total electricity mix. The Turkish government recently announced plans to increase coal-fueled generating capacity from the current level of 17.3 GW to 30 GW by 2023 to further increase its independence from imported Russian natural gas. Following an extensive due diligence initiative of the available CCP sources of supply, ZAG has established a long-term, secure supply position directly with the most reputable Turkish utilities. The combination of large-scale availability of CCPs for export, the proximity to end-use markets, and access to deep water ports will assure customers in the Americas of a reliable, long-term supply solution.

Africa

South African Flt Ash used to help build the continent’s longest suspension bridge.

The project is one of the major capital investment initiatives undertaken by the Government of Mozambique, which appointed the China Road and Bridge Corporation as the main contractor and GAUFF Engineering as consultant. The bridge, built over the Bay of Maputo, has an open span of some 680 meters and a clearance height of 60 meters to accommodate the bay’s very active shipping lane.

Providing a connecting route that will trim road-based transportation times to South Africa—from which Mozambique imports many of its staples— by at least three hours, the bridge is expected to open new investment options in the region. With sustainability a critical consideration in the bridge’s construction, balancing social, environmental, and economic factors required innovative thinking. This led to the choice of substituting at least 35% of the cement in the concrete with South African fly ash. The reduced emissions associated with the use of the fly ash at 2 kg CO2 e/ton—compared to cement at 840 kg CO2 e/ton—yielded substantial environmental benefits.

Concrete Mixture:

Two computerized batching plants are dedicated to the construction of the Maputo Bridge. One plant is situated in Maputo and the other is in Katembe. Both plants are within 2 kilometers of the site. The capacity of each plant is 120 m³ per hour. Fly ash supplied by Ulula Ash is transported from South Africa to Cemento Maputo in Matola approximately 15 kilometers away and is stored in large silos at the respective batch plants. Aggregates from four suppliers are stockpiled on site to ensure the ability to produce concrete 24 hours a day, 7 days a week. The contractor has 12 approved mixture designs.

The siliceous fly ash used complies with the SANS specification and provides the following benefits:

• Increased later-age strength—for example, at 90 days
• Reduced rate of chloride diffusion through the concrete
• Prevention or retardation of alkali-silica reaction
• Reduction in rate of heat generation by up to 20%
• Reduced shrinkage due to lower water demand
• Significant reduction in the risk of thermal cracking
• Improved sulphate resistance.

Physical testing is being performed in the on-site laboratory to confirm the results received. High workability of the concrete was one of the main design parameters. Constructing piles 110 meters deep, and pumping the concrete to a height of 140 meters, meant that a very fluid concrete was required.

Project participants:

• The Government of Mozambique, represented by Empresa de Desenvolvimento de Maputo Sul.
• GAUFF GmbH & Co. Engineering KG, Nuremberg, Germany/ Maputo, Mozambique.
• China Road and Bridge Corporation, Beijing, China.

Resources:
http://www.globalcement.com/news/itemlist/tag/Fly%20Ash?start=0
https://www.youtube.com/watch?v=t6bfpZ-8Wu8&feature=youtu.be
https://www.acaa-usa.org/Portals/9/Files/PDFs/ASH01-2018.pdf

Ksenia Kaplieva-analyst