Spotlight Feature Articles MINE SAFETY - Page 5

MINE SAFETY standards , some 40 litres / min per person must be supplied to remove carbon dioxide or dangerous gas mixtures exhaled via the safety valves , with used oxygen returned to the atmosphere .
The combination of the system components enables the constant maintenance of an overpressure of at least 100 Pa in the driver ’ s cab and in the cassette , as well as the prevention of methane inflows , according to PAUS . The quality control of the air , humidity in the driver ’ s cab and the cassette of the MRV 9000 are carried out with Dräger ’ s multi-channel X-am series gas detectors . After the mine rescue team leaves the vehicle , the composition and air supply are adjusted to the minimum permissible value with the help of control elements , PAUS explains .
As contaminated mine air still enters the driver ’ s cab and the cassette through the door openings after the mine rescuers have left the vehicle , the flushing mode with air supply up to 1,000 litres / min is switched on to displace the air via valves . When the gas measuring devices register the normal defined quality of the air , the mine rescuers and those being rescued can switch off their respirators .
The reserve of the breathing mixture , compressed to 300 bar and stored in six cylinders with a capacity of 50 litres each , is stored in two chambers with three cylinders each . This block with three cylinders is connected to the control units in the driver ’ s cabin and in the rescue cassette by a reducing valve , which cuts the pressure of the mixture . The pressure and air volume in the cylinder block are seen on special monitors in the driver ’ s cab . With this information , it is possible to determine the time available to the mine rescuers for the recovery operation .
The set of six air cylinders with a capacity of 50 litres each is adequate for : n Moving a unit of six mine rescuers ( two in the driver ’ s cab , four in the cassette ) to the emergency location within 60 minutes ; n Five mine rescuers performing work in the emergency zone ( one member of the unit remains in the driver ’ s cab ) for 120 minutes ; and n The return of the unit of mine rescuers with six people ( together with three injured personnel ) within 60 minutes . With such breathing capacity ( in six cylinders ), it is permissible to switch on the purging mode as follows : n In the driver ’ s cab , three times for a period of three minutes each time ; and
n In the cassette , three times for a period of eight minutes each time . In this way , the mine rescue vehicle can allow the rescue team four hours of transportation in an atmosphere unsuitable for breathing .
A safe place
There are occasions when a mine rescue mission cannot be conducted immediately , meaning those stranded individuals underground need to get to the nearest safety chamber to avoid injury and await their rescue .
In May , Strata Worldwide released its next generation emergency refuge chamber , the Strata ERCX , a unit intended to provide greater flexibility for custom configurations , which factored in “ many time-learned improvements for occupant safety and comfort ”.
The global launch saw the steel-sided , walk-in refuge chamber become available to the underground mining , tunnelling , chemical and other industries where emergency isolation for workers may be required .
An update on the company ’ s ERC chamber , the ERCX is available in four standard sizes – 8- , 12- , 20- and 26-person – and has select base configurations . It also boasts a comprehensive list of customer preferred options , according to Strata .
“ These options range from structural modifications , such as wheel and hitch packages and airlock entrance compartments , to highly sophisticated communications and remote monitoring systems that include several options for establishing a live connection to the surface ,” the company said .
Strata ’ s David Maust sees the CSE product line , which includes a range of SCRSs , complementing the new ERCX rescue chamber
David Maust , General Manager of Emergency Refuge Chambers – Americas , talked IM through some of the changes from the ERC to the ERCX :
“ This includes improved seating and comfort ; additional space and volume per occupant ; an optional automated oxygen control system to eliminate the need for manual adjustments by occupants ; an improved and highly efficient air conditioning system designed to remove moisture and heat generated by the occupants ; an improved escape hatch and door latching system for easier operation and improved air tightness ; and the addition of a remote monitoring and communication system that will provide rescue teams valuable information during a mine emergency ,” he said .
The ability to customise these chambers will be of the utmost importance to the ERCX gaining traction across the globe .
Maust explains : “ For example , there are Latin American countries that require 48-hour duration chambers ; others 72 hours . The chambers we are manufacturing for Russian coal applications are rated at 96 hours . US coal chambers are mandated to meet a 96-hour duration while the US does not have a chamber mandate for metal / non-metal mines . Thus , US metal / nonmetal chamber durations vary based on the customer requirement .”
Other regional variations the company is equipped to deal with include :
OCTOBER 2020 | International Mining