At bauma China 2012, Sandvik introduced the DH350 down-the-hole (DTH) surface rig, described as “the right choice” for those seeking an economical, simplified-to-use and reliable drill. The DH350 is diesel-powered and track-mounted, designed to use 3-, 4- and 5-in. (75-, 100- and 125-mm) DTH hammers for hole diameters ranging from 89–152 mm (3.5–6-in.).
The 7,300-kg (16,000-lb) DH350 features a rigid fixed boom and feed design and efficient hydraulics for boom positioning, feed, rotation, tramming and track oscillation. Operational productivity, hole accuracy and drilling smoothness are enhanced by a heavy-duty rotary head rated at 2,530 Nm torque. The rig is equipped with a 43-kW diesel for drilling and ancillary power; to reduce fuel costs, it depends on an external compressor powered by an independent engine to provide air for the hammer and hole flushing.
Drilling functions are centralized in a single control panel, and a separate tramming control station is located at the rear of the rig, along with an operator transport platform. Daily service points are within easy reach from the ground level.
According to Sandvik, the DH350 initially will be offered only for the Chinese market.
Atlas Copco’s latest rotary surface drill, the Pit Viper 311, was unveiled at MINExpo 2012 and is the first model in an all-new Pit Viper 310 series. The 311 can be configured to drill to 65 ft (19.8 m) in a single pass or to a maximum depth of 125 ft (38.1 m) in two passes.
Atlas Copco said the PV-311 offers a narrow hole-diameter range of 9 to 12.25 in. (228 to 311 mm), to fill a gap between the hole ranges offered by its Pit Viper 351 and Pit Viper 270.
The Pit Viper 311 offers power options that include Tier 4 and Tier 2 diesel engine alternatives. The tower has an interchangeable unit, structurally similar to the Pit Viper 351, but is deeper to accommodate larger sheaves for either single-pass or multi-pass applications. Weldments have been improved, and a ladder now provides access to decking above the rod changer when the tower is horizontal.
The two-speed hydraulic rotary head delivers 12,880 ft-lb (17.500 Nm) of rotation torque at 140 rpm and 7,000 ft-lb at 240 rpm. Hydraulic cylinders drive the cable feed system, and the patented automatic cable tensioning system reduces cable and rotary head guide wear by continually keeping the rotary head aligned.
Standard across the Pit Viper range, including the Pit Viper 311, are a hydraulically powered breakout slide wrench and a hands-free auxiliary hydraulic wrench with a 6-in. clamp cylinder. The fork chuck features an improved deck bushing.
Atlas Copco offers a number of options for the Pit Viper 311, including a new automatic hydraulic clutch designed to decrease fuel consumption during non-drilling operations. In addition to standard safety and interlock features, the unit’s Rig Control System supports auto-level, auto-drilling, GPS hole navigation, wireless remote tramming, and more.
At MINExpo, the company also noted that the Pit Viper 316—an extended multi-pass version of the Pit Viper 311—was under development, and when available will be capable of drilling to 295 ft (90 m) using a five-rod carousel with 50-ft drill pipe. The Pit Viper 316 is scheduled to be launched during 2013 as a replacement to the DM-M3 model and is designed specifically for cast-blasting applications in coal mining.