Making Mines Safe
Making Mines Safe
Safety in the coal mining industry has recently moved up the political agenda in both the Western and Asian markets. An in-depth look at the Crandall Canyon disaster assesses what lessons have been learnt and how mine safety is to continue improving.
Crandall Canyon, of Emery County, Utah, will long be remembered as the site of one of the worst mining disasters of recent years to take place in the US.
The collapse of the mine back in August 2007 sent shockwaves through the mining community. The events that unfolded over the following days – including the death of the six miners trapped underground and three rescue workers tasked with saving them – dominated US headlines for months.
More pertinent to the mining industry, Crandall Canyon raised serious questions about the safety of coal mining operations in the US and the rigour of its regulatory bodies.
WHAT HAPPENED AT CRANDALL CANYON?
On 6 August 2007, a ‘mine bump’ took place that registered 3.9 on the Richter scale. This bump – more accurately described as a catastrophic structural failure – collapsed the mine’s Main West chamber, trapping six miners more than 1,500ft underground. So intense was the bump that it knocked out ventilation stoppers over a mile away from the accident site.
Disaster response teams were dispatched to Crandall Canyon mine immediately, but initial attempts to rescue the trapped miners were slow as rescue teams set about clearing a pathway. Having breached the Number 1 seal in Main West, they came up against a massive coal blockage – which estimates put at taking between two and six weeks to clear.
On 9 August it was decided to sink a number of bore holes, in order to more accurately establish the position of the men by analysing air samples and sending down microphones. Over the next few days further bore holes were drilled, as underground rescue teams continued to make their way through the rubble. Tragically, on 16 August, the mine collapsed again, this time killing three rescue workers and injuring six others. All further attempts at rescue were abandoned.
MINE SAFETY AND EMERGENCY RESPONSE
In the aftermath of the collapse, a number of reviews were implemented to get to the bottom of what actually happened.
The Mine Safety and Health Administration – MSHA, the state body that regulates the mining industry in the US – initiated its own investigation and committees in both houses of Congress continue to review events.
Additionally, the Utah Mine Safety Commission was set up with the remit to examine the role of the state in coal mine safety. Reporting in January 2008, it overwhelmingly concluded that there was much more that could be done. Increased state safety oversight, more effective use of technology and clear lines of command when it came to emergency response were just some of the bases touched by the report.
Commenting, Commission Chairman Scott Matheson said: “We have learned in this process that the state of Utah does about as little as any other state to promote mine safety.” Damning, yes, but not entirely surprising.
In 2006, US mine safety regulators failed to conduct inspections required by federal law at more than one in seven of the country’s 731 underground coal mines.
That same year the number of deaths in US coal mines was 47, double the number in 2005. Before Crandall there were the Sago, Aracoma and Darby disasters. With each case, the considerable media fallout pointed the finger at the HMSA. Accusations of mismanagement and lack of funding have been laid squarely at the feet of the HMSA and national government.
WIRELESS AND ELECTRONIC TRACKING SAFETY SYSTEMS
More recently, steps have been taken to increase mine safety. The MINER Act, introduced following the Sago disaster in 2006, largely focused on the development of enhanced communication technologies to improve post-accident communications. These included the use of wireless systems and electronic tracking.
It also focused on the modernisation of emergency response plans, requiring every mine to continuously develop their written contingency plans.
A principle worry remains for some that as the demand for coal rises, infrastructure and maintenance is being left behind. The events of Crandall Canyon brought into sharp relief once again the need for rigorous regulation and management to ensure that safety legislation is adhered to.
According to some commentators, the necessary rules and regulations – such as the MINER Act and recent amendments made to it – are in place, but the political will is still playing catch up. Unfortunately for the nine people that died, Crandall Canyon got caught in that crossfire.
CHINESE MINE SAFETY – A CONTRADICTION IN TERMS?
How does the Chinese mining industry compare? As a starting point, it is renowned for being the most dangerous in the world. Accidents on the level of Crandall Canyon occur on an almost daily basis. For 2005, official government figures put the number of mining-related deaths at around 6,000.
After a decade of rapid economic growth, China has more than doubled its coal production, with 2.53 billion tonnes produced in 2006. This high energy demand coupled with high prices has, in terms of mine safety, left the industry on its knees.
However, there are emerging signs that the Chinese mining industry is turning the corner. In January 2008, figures reported by the Chinese government showed a 20% reduction in deaths on the previous year; although still the highest in the world, this signifies a substantial reduction.
Additionally, it was reported that over 11,000 small mines have been shut down over the last three years as part of a crackdown on poor safety conditions – these small mines being responsible for a vastly disproportionate amount of deaths.
As a short-term strategy for improving mine safety, this appears to be working.
One of the major problems with the Chinese mining industry has long been the small, barely regulated, village and township mines. Shut these down and half the problem is solved almost immediately. But the Chinese government is also looking at longer-term solutions to improve mine safety.
Many of the problems that are currently being experienced in China have already been faced, and solved, by the more experienced mining countries.
There is growing willingness on the part of international organisations to support initiatives to improve health and safety. It could just be as simple as exporting the knowledge.
TECHNOLOGY BOOST TO MINE SAFETY
Already, China’s coal consumption sector is utilising some of the cleanest coal technologies available. The EU and the US have invested in major technology transfer projects to work towards cleaner plants, including carbon sequestration.
The coal production sector is starting to follow suit, using improved technology to boost safety. The State Administration of Work Safety (SAWS) recently announced that it would be promoting the use of tracking and locating systems for use underground.
The introduction of real-time supervision systems is in line with government objectives and should be able to identify the exact location of trapped miners and assist rescue teams in analysing the underground environment. Honeywell’s ‘Miner Management and Locating System’ was unveiled in China recently, designed to meet this exact need.
This collaboration between international big business and the Chinese authorities is a good indication that the safety issue is being taken seriously. But it is not the be all and end all – technical improvements can help but without proper training and usage they could be rendered ineffective. Another aspect to solving the mine safety issue is the sharing of expertise as well as technology.
Over recent years, the Chinese authorities have enlisted international help in training for mine managers, foremen, rescue workers and government regulators.
The International Labour Organization (ILO) has become involved, brokering talks between mining companies, government and trade unions. Miners’ safety groups are being developed and 100,000 mine safety representatives were recently appointed.
The future would appear to be bright, but there are many obstacles still in the way. The problems of deregulation largely remain, and illegal mining – especially in these times of high demand – remains a major problem.
The drip feed of 24-hour news coverage around the world has added further incentive for the government to sort things out. But with continued action towards improving mine safety, headlines heralding coal mining as ‘the most deadly job in China’ may start to become a thing of the past.
A Greener Future for Coal
A Greener Future for Coal
How the coal-mining industry is aiding the fight against carbon emissions by recovering methane.
With the rise in energy demand has come a growing need for coal, still the prevailing source of energy for power plants around the world. But today, the coal power industry faces new pressures, not only with production, but with its carbon footprint right along the line.
Today, the scrutiny goes all the way back to the initial process of getting the coal out of the ground. Methane (CH4) is given off when organic matter decays, and so coal mines (also landfill sites) are a rich source of the gas. The quantity of gas released from mines increases mainly with coal carbon content and coal depth.
Particularly as the deeper coal deposits were formed, high temperatures and pressures forced methane into micropores within the coal. Huge amounts can be adsorbed, with just a gram of coal estimated to have a surface area of up to 250m2 or more.
While coal is being mined, the methane escapes and mine ventilation systems have to drain it to prevent explosions. The low concentrations have made this coal mine methane (CMM) difficult to recover from working mines, but that is now changing.
The richest sources, though, are mines before they are worked (coal bed methane, CBM) and after they are closed (abandoned mine methane, AMM). Coal mining operations normally cause subsidence and fractures in the layers around the worked seams. Old workings therefore become large gas reservoirs and will gradually release the gas to the atmosphere.
CH4 has around 20 times the global warming potential of CO2 and, in 2010, worldwide coal mine methane emissions are expected to total 400 million tonnes of CO2 equivalent and rising. Besides adding to global climate change, simply allowing methane to vent to the air wastes a valuable resource.
Recovering and using the gas is profitable. Recovered methane can fuel vehicles, boilers and district heating systems, dry coal, generate electricity or be injected into natural gas pipelines (methane is the largest constituent of natural gas). It also has industrial uses, for example being a feedstock for producing carbon black, dimethyl ether (DME) and methanol.
Global coal mine methane emissions actually declined between 1990 and 2000 because many deep coal mines closed. This happened in China, the largest methane-emitting country, in the second half of the decade. It happened in Former Soviet Union countries, which also saw restructuring of the energy industries. It happened in the US, where there was increased methane recovery as well as a move to surface mining, which releases much less methane. It also happened in Europe, with further methane reductions aided by EU waste disposal directives.
Emissions are on the rise again now, though, particularly in the developing world as a result of industrialisation and fast-expanding populations and economies. Wherever coal production is planned to increase, methane emissions will also rise unless the gas is recovered.
It is much easier to prevent non-CO2 greenhouse gases emissions than CO2 emissions themselves, and the US in particular has focused its attention on methane. The Methane to Markets Partnership was launched at the end of 2004 in Washington DC, the US, with 14 national governments signing on as partners. From the US, too, the Environmental Protection Agency (EPA) encourages recovery internationally with its voluntary Coalbed Methane Outreach Program (CMOP).
The EPA indicates three major abatement systems: degasification, enhanced degasification and oxidation of VAM.
RECOVERING THE METHANE
Degasification recovers high-quality CH4 from coal seams. Vertical wells can be drilled up to ten years before mining operations, or horizontal boreholes up to one year or less before. High-quality CH4 also often can be obtained from gob wells (from around mined-out coal seams), with gob gas CH4 concentrations ranging from 50% to over 90%.
The recovered gas can often be injected into a natural gas pipeline, with the US estimating that nearly 60% of mines at first require virtually no purification, although this may be needed later. This is the simplest form of recovery and the upfront costs (for equipment like compressors, gathering lines and dehydrators) and annual costs (mainly drilling costs) are repaid by cost savings from capture and reuse. Where it cannot be injected into pipelines, the methane can be used as a fuel source for gas engines and generating electricity; this method is particularly advanced in Germany and France.
Enhanced degasification recovers methane in the same way, but enriches it using equipment like nitrogen removal units (NRUs) and dehydrators. Upfront costs include an additional $200,000 for the NRU, and higher annual drilling costs because the wells are more closely spaced. The enhanced gas recovery (particularly for medium-quality gas), however, makes another 20% of mines profitable.
Ventilation air methane oxidation removes the gas from working mines using large ventilation fans. Until recently, the low (typically below 1%) methane concentrations in VAM prevented its use. VAM can be burned (CH4 + 2O2 –> CO2 + 2H2O), to heat water – for steam or district heating – or generate electricity. Upfront and annual costs of such thermal or catalytic oxidation depend on concentration and the ventilation air flow rate.
WHERE ARE METHANE RESOURCES?
The US EIA (Energy Information Administration) estimates that 60% of the world’s recoverable methane reserves are located in China (12%) and the Far East, the Former Soviet Union (23%) and the US (25%).
Without major recovery initiatives, emissions will grow quickly in South and East Asia.
The largest coal consumer and producer is China, producing around 1 billion metric tons of underground coal a year. The country has a history of CMM recovery dating back to the 1950s, and surface CMM development began in the 1990s. China now reuses around a third of the total methane drainage, but its methane emissions are expected to increase 50% by 2020 and there is great scope for increased recovery.
With a production of 430 million tonnes, India is the world’s third-largest coal producer and its production will potentially double by 2010. There is interest in reclamation and in 2007 Coal India Ltd (CIL) invited interested parties with proposals to recover methane from existing and abandoned mines (largely located in the Jharia coalfields).
In Russia, natural gas emissions dominate and are expected to increase. Polish emissions are expected to decline sharply by 2010, largely due to predicted closure of many privatised mines. The Polish economy is still largely coal based, though with negligible natural gas and oil reserves. Methane recovery and use could increase as mines try to remain profitable.
Elsewhere, emissions have grown strongly in Latin America, but have slowed since the early 2000s in the Middle East, Africa and the OECD countries.
The OECD countries have in fact seen some of the lowest growth rates. This has largely been caused by limited production growth and air quality equipment that has also reduced methane emissions, although natural gas use itself is predicted to grow.
The US has a good recent record of methane reclamation. In 2005 it recovered nearly 80% of all drained CMM.
Active coal mines account for nearly 10% of US anthropogenic methane emissions, and the EPA has identified another 400 promising ‘gassy’ abandoned mines. These are mainly located in the Appalachian Basins in the East, Black Warrior Basin in the South, the Illinois Basin in the Central US, and several western basins such as the San Juan and Powder River Basins.
Here and elsewhere, recovery methods are improving. Particularly, techniques like enhanced coal bed methane (ECBM) look promising. This injects gas – typically nitrogen or carbon dioxide – into coal seams to improve methane recovery like enhanced oil recovery improves oil recovery. Assuming early tests are successful, the technique could be a good candidate for carbon sequestration, particularly for projects receiving carbon credits.
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