RAMESH KUMAR G highlights the importance of portable air compressors and explains why they can be called the heart of construction and mining industry operations.The construction industry in India plays a key role in urban development and is expected to record a CAGR of 15.7 per cent to reach $738.5 billion by 2022. India is also likely to rank among the top three in the global construction market. Following the growth trajectory of construction, mining is another closely related industry recognised for employment, revenue generation, and value addition to other sectors. Even though its tempo slowed down due to the COVID-19 outbreak, mining will continue to be a pivotal contributor to the Indian economy, supporting real estate, mineral, steel and cement production, and power generation. Air compressors are primary sources of power for equipment and machinery used in the construction and mining domains. These sectors employ a variety of portable compressed air systems that offer reliable high-pressure air to power pneumatic equipment. While choosing air compressors for myriad activities in these industries, it is essential to understand the airflow and pressure requirements of individual applications. With free air delivery matched to demand and ease of maintenance, ELGi’s air compressors support several construction and mining applications, including: Sand and shot blasting Sandblasting helps clean surfaces with a jet of sand driven by pressurised air. It is used to remove rust, old paint crusts, and other impurities. The process helps make rough surfaces ready to precede activities such as polishing and coating. Shot blasting is another surface treatment process that uses high-speed steel abrasion to clean and prepare surfaces for secondary finishing operations. Optimum Airflow or free air delivery along with pressure is essential to obtain the desired Surface finish for this application. In blasting, air directly pushes the material used for cleaning the surface. Depending on the size of the nozzle, the airflow varies between 70 to 750 CFM. Rock anchoring An important procedure used in construction, rock anchoring stabilises the foundation of large structures. The process involves drilling a hole of a pre-specified size up to a suitable depth in a rock. A rock anchor tendon is then inserted and fixed to the rock. The anchors grouted inside the hole are usually made up of steel bars or strands to offer lateral force to the retaining structure and prevent it from shaking or moving. The application is commonly used in foundation works and for highway construction in hilly areas. ELGi’s air compressors with 300 to 450 CFM of airflow at 7 to 10 bar pressure are frequently used for drilling works in rock anchoring applications. Cable blowing Cable blowing is used to install optical fibre cables in pre-installed ducts. To execute this, the cable is manually pushed into the duct for a few metres and compressed air is injected through the cable blowing machine inlet for taking the cable further into the ducts. This pressurised air flows along the cable at high speed. A cable blowing machine applies the pushing force near the cable inlet. Depending on the duct route, it is feasible to install an optical fibre cable measuring more than 1000 metre in length using such blowing methods. Shotcrete technique (concrete spraying) Shotcreting or concrete sprayer technique optimises the process of spraying concrete on thin overhead horizontal or vertical surfaces. It is particularly used for curved or folded sections, canals, reservoirs, and tunnel linings with variable tunnel cross-sections. In this application, high-pressure air runs a cement-sand mix in the ratio of 1:2 or 1:3, depending on the requirement. The concrete sprayed on surfaces reinforces tunnel walls and roofs to prevent them from collapsing. Blue metal quarrying Blue metal quarrying is a ground drilling application where several holes having diameter sizes between 1’’ to 4.5’’ are bored into a rocky ground using equipment such as jackhammers, wagon drills, and crawler drills, which are operated by powerful air compressors. In this application, the air compressor is largely a stationary asset, and the drilling devices become the moving members to make holes in the ground. The holes are further blasted with a series of explosions to derive stone particles. The devices powered by air compressors for blue metal quarrying include: Jackhammer with a rod diameter between 1” to 1.5” and rod length between 6 to 20 ft. Wagon/Crawler drill with a rod diameter of 4.5’’ is used for a drilling depth of 45 to 60 ft. The air compressor selection for such applications depends on individual project requirements and equipment used for quarrying. The size and depth of holes to be drilled are other factors to be considered when choosing an air compressor. Coal mining In coal mining application, before extraction of coal, overburden on the surface is to be removed. Air compressors play a major role in removing the overburden by drilling 6.5” diameter holes up to a depth of 6 metre. There are two types of drilling rigs used for this application: Truck-mounted drilling rig with compressors: This is a conventional method of drilling and the process requires establishing the stability of the structure to ensure the safety of the drilling personnel. However modern drilling methods have evolved with better safety and ease of drilling operation. Excavator-mounted drilling rig and compressors: To apply better safety norms in mining activities, the Directorate General of Mines Safety (DGMS) has instructed miners to use track-mounting with excavators at their sites. ELGi’s PG 550S-200 air compressor is a preferred choice with the contractors for this application. Granite and marble mining Granite and marble mining involves the extraction of raw forms of blocks that are later shaped into slabs used for flooring, countertops, and other surfaces in construction work. ELGi’s energy-efficient and robust air compressors make granite and marble mining operations more productive and cost-effective. Pigging Devices called pigs check the conditions inside pipes and clean them. In the process industry, pigging helps clean pipelines with large diameter. However, many continuous and batch plants today have smaller diameter pigging systems as they are more efficient. Summing up Construction and mining activities supporting housing and infrastructure development in India will be significant in laying the groundwork for smart cities and factories of the future. And the efficacy of these processes relies on the equipment used to fuel them. Here’s where air compressors play a major role in powering drilling equipment in various applications across construction and mining industry. About the author: Ramesh Kumar G is General Manager-Portables at Elgi Equipments.