While the introduction of alternative fuels and raw materials brings many benefits to the cement plant and its surrounding community, the process requires putting in place an appropriate health and safety management programme. David Gossman of Gossman Consulting, Inc (GCI), USA, offers several important points to consider.
Alternative fuels and raw materials (AFR) present hazards well outside of those normally found in a cement plant. Some of these hazards are obvious and relatively straightforward to deal with. For example, flammable liquid wastes present fire hazards for which there are standards that cover storage, transfer and transport that have sound historical basis and require little more than proper engineering and training of personnel operating the facility. Because of the wide variety of mechanical hazards already present in a cement plant, the processes of shredding, grinding, conveying and similar mechanical systems for AFR are also easily accommodated in cement plant operations and safety plans. Nevertheless, there are mechanical hazards involving flammable-liquid pumps and shredders that have resulted in at least one fatality in the industry, so special care is still needed.
Hazards that require special concern and control in handling and using AFR include toxins, reactive constituents, biological hazards and ionising radiation (radioactive materials). "Wait," you say, "we don’t handle anything like that in our AFR programme.'"Please, don’t be so certain of that and read on.
Toxins come in two forms, acute and chronic. If a plant is handling flammable liquid wastes or sludges then it is probably handling both classifications of toxins whether it is aware of it or not. Does the facility have a programme to test for and identify these toxins? Does it reject those that its personal protective equipment (PPE) and other safety systems are not designed to handle? How about alternative raw materials? Has the works ever seen PCBs in waste sand from another manufacturing facility? How about dioxins in dross used as an alumina source or iron oxide byproducts used as an iron source? All of these incidents have happened.
Reactive materials can also come in both liquid and solid form. How about the non-flammable still bottoms from a chemical process that, after being heated in the rail car for direct feed to a cement kiln, exploded and turned the pressure-rated rail car into a piece of popcorn and sent it over 210m through the air, trailing flaming debris that took out both the plant power control centre and the liquid waste fuel facility?
Waste fuel facilities that shred and blend solid waste-derived fuels have a long history of fires from reactive materials inadvertently being mixed. Even iron oxide from the bottom of a drum getting caught in a filter catalysed a reaction in an otherwise benign material and caused it to ignite explosively at a waste handling facility. There are even raw material substitutes in the industry classified as non-hazardous that can create flammable vapours on contact with water. For that matter, most people who have been around in the cement industry in wetter climates where coal was used, have seen spontaneous fires in coal piles. If that can happen with coal, one can be certain that AFR can also have problems that might otherwise be unexpected.
Biological hazards are most often associated with handling medical wastes and for that reason most AFR programmes exclude medical waste. The problem is that this is wrong for two reasons. First, medical wastes that have been properly treated in an autoclave are quite literally sterile – far more so than anything else you would find in a cement plant. There is real potential to turn these wastes into an excellent fuel called PELLA-DRX™, a process patented by Sharps Compliance Inc. 1 On the other hand, it is hard to imagine a more potent potential vector for introducing naturally-occurring pathogens in a cement plant than the sharp wires found on shredded tyres.
Ionising radiation (or radioactive materials) can be found almost anywhere. Some are naturally occurring, while others are manmade and often occur in some of the most unexpected sources. Whether it is a radioactive solvent that was introduced into a blended liquid fuel from some hospital waste where it is used to treat cancer, or old piping removed from oil wells, or a shredded smoke detector that ends up in a mixed-plastic shredded fuel stream, this hazard can create real emission and product liability problems for a cement plant. Luckily, it is easy to test for 2 and avoid.3 So why aren’t more facilities actually carrying out this testing? This a low-probability, high-consequence event with a very low cost to prevent.
Often the response to these concerns is to point to the extensive maze of regulatory controls in most countries to control hazardous materials. The problem is that when applied to many waste management and recycling operations, these regulations are both inadequate and contain exceptions to the normal rules that apply to hazardous materials. For example, in the US both OSHA and MSHA exempt waste materials and fuels from having material safety data sheets (MSDS). It is also often the perception that environmental practices and regulations are protective of human health and safety. While that is often true relative to protecting the public, it is not necessarily true for those working inside the plant. The US EPA has even admitted this. In one document,4 a case study of an explosion at a fuel blending facility in Oklahoma, the EPA stated in the introductory paragraph: "Major chemical accidents cannot be prevented solely through command and control regulatory requirements; understanding the root causes of accidents, widely disseminating these lessons learned into safe operations are also required." That is an extraordinary admission from one of the US government’s most regulation-prolific agencies.
GCI is often reminded by these situations of the title of a short story written many years ago by Robert Heinlein, entitled "Blowups Happen".5 The fact is that the examples given regarding prior incidents at cement plants and waste processing facilities are real. In addition, the company has seen fires on kiln floors involving flammable wastes and fires from trucks unloading wastes. Fires on feed belts are also relatively common. There have been both loss of life and limb in AFR facilities. As an industry there is a responsibility to the workers in the plant and the shareholders of the companies to do everything practical to prevent these sorts of incidents in the future.
Safety management systems
The management of AFR is inherently complex. Unlike a chemical production facility, which handles tonnes of the same 10 or 15 chemicals year-after-year, an AFR facility often handles tonnes of maybe 100, 200 or more chemicals each year and often at a receipt frequency that lulls management into a routine that has not addressed all of the variables that each waste receipt presents. AFR, after all, is usually derived from a waste or byproduct and not from a specification product. Every receipt should be approached as if it were a ‘surprise’ no matter how often similar material has been received or how consistent the generator has been. Yet, initiating safe practices beginning at time of receipt is starting too late. The safe management of AFR has to start when the facility is first planned and the people first hired. Moreover, it must be systematically unrelenting thereafter.
Multiple failures of elements of a safety management system are the cause of catastrophic accidents, not that last fatal act by an unaware operator. It is extremely rare for a failure in safety controls to be 100 per cent caused by a single failure. The key is a sequence of preventative steps designed to put multiple layers of controls in place so that if just one failure happens there will be no negative consequence.
One accident, many failures
|In the EPA case study noted previously, the story is simple. About 200 gallons of waste solvent was mixed with about two gallons of dry oxidisers (pretty small quantities when you consider the scale of most AFR operations): a mixture of chlorates, perchlorates and nitrates. In less than a minute this exploded out of the mixer, fatally engulfing one man and starting a large fire in a building storing flammable liquids. Clearly, mixing flammable liquids with oxidising chemicals is an unbelievably stupid thing to do – but it happened. It happened because the full nature of the chemical characteristics was not investigated and understood, so that a plan of action could be proposed and that proposal evaluated for safety. Subsequently, the approved plan could be presented as a standard operating procedure (SOP) and the operators trained to safely execute the SOP. It may be that there was no safe way of doing this, but in that case the initial investigation would have made that determination.
In the end the preventative steps drawn from an examination of this one simple incident are the same ones GCI has advocated after every accident the company has investigated and prior to operation of every facility set up. Quoting from the case study, those preventive steps are:
• “The chemicals and reaction mechanisms associated with the substances mixed or blended must be well understood and documented. Facilities need to conduct the necessary information searches or laboratory tests to ensure that all reaction mechanisms are known and documented, especially those that may trigger fires or explosions as a result of abnormal situations or changes in chemicals or materials mixed
• Chemical and process hazards must be understood and addressed. Once the reaction mechanisms are well understood, facilities need to ensure that process equipment, controls and procedures are designed, installed and maintained to safely operate the process. A formal hazard review using techniques like ‘What-If’ or ‘HAZOP’ can help identify opportunities for failure (eg human error, mechanical failure) and layers of protection to minimise the consequences of such failures, based on established codes and standards, industry practices, (federal or state) regulations and common sense
• All employees need to understand the chemical and process hazards. All personnel should openly communicate information about hazards and process conditions and understand the consequences of deviations and unusual situations. Facilities should establish mechanisms for documenting and sharing such information
• Standard Operating Procedures (SOPs) are essential to safe operations. Facilities should establish a system to develop and maintain written SOPs and ensure that they are understood and followed at all times. The SOPs must address all phases of operation, safe limits for operation, consequences of deviation and identification of corrective measures during emergency situations
• Before starting a process or procedure that has been changed or modified, the chemical and process hazards must be evaluated. Abnormal or non-routine circumstances are a leading factor in chemical accidents. Facilities should make use of management of change (MOC) and pre-startup safety review techniques to ensure that modified processes or procedures will function as intended without unanticipated impacts on other operations
• Employees must be properly trained in the processes they work on using the SOPs for that process or job tasks. Training must include potential hazards, reduction of those hazards, safety consequences if procedures are not followed and proper emergency response to abnormal situations. Training should contain clear and concise objectives that can be easily evaluated for operator competence.” 5
In some of the more spectacular incidences that GCI has examined, every one of these steps were either ignored or truncated.
H&S risk control tools
There are a wide variety of risk analysis tools that can be used for both new and existing processes. The HAZOP process 6,7 mentioned previously is an excellent one that GCI has used in the waste recycling environment to evaluate new and existing systems. Other processes such as a Root Cause Analysis are likely more appropriate when there are incidents or other failures in the safety management system even if they do not result in an incident.
Audits, both internal and external, are useful tools in identifying gaps in an existing safety management system as well as identifying actual compliance with said system. It is usually a good idea to perform such audits at the direction of counsel, where allowed by law, to protect the company from over-zealous government enforcement personnel. The result of a good audit is not a list of ‘problems’, ‘compliance issues’ or ‘violations’ but rather a series of prioritised action lists that are developed with facility management and staff.
An important aspect of any AFR programme is a safety review that is carried out in parallel with a process compatibility review prior to accepting or processing any AFR. This task may need to include a review of the process producing the AFR, including the original generator source and any intermediate processing facilities. A material broker or processor does not necessarily have the same motivational drivers to look for problems as the end-user cement plant. We have all heard the phrase 'trust but verify.' In this industry, forget the 'trust' – just verify. That usually means testing, either testing by the cement plant or by the supplier, with some sort of audit or verification system of the test results. The range of test parameters and methods can vary considerably based on the AFR type and the set data quality objectives (DQOs). While it is often claimed that some sorts of testing are too expensive or time consuming to be practical, GCI has rarely found that to be the case. Moreover, when a reluctant management finally does implement the use of a new (to them) testing methodology, they often discover previously unsuspected financial and productivity advantages.
There are frequently situations when the cement plant already has the necessary laboratory equipment, just not the knowledge or experience to understand how it can be used to accomplish the quality control needed for an AFR. Too often the manager in charge of the AFR programme does not have the background in chemistry to understand what data is required or how to obtain it – those issues can be overcome with outside assistance. Of greater importance is the training on what to do with that data. It is easy to determine if an AFR fuel meets a heat content or chlorine content specification. It is much more difficult to determine, based on a chemical analysis or information about the source of the AFR, whether or not that material might create a reaction or toxic exposure hazard. It is critical for any AFR programme that personnel with the expertise for those evaluations must call the shots on what is handled and what is not. Never let sales and marketing make those decisions for operations.
If wastes containing any level of toxicity are being considered for use as AFR, an additional system to both evaluate those hazards on a compound-by-compound basis as well as in combination is required. It is easy to specify PPE for handling a single compound or product. It is not so easy when dealing with a mixture of a large number of materials or chemicals that can vary from day to day and shipment to shipment.
Many companies have developed sophisticated models that to help to determine if a prospective material can be handled with the standard PPE that is used in the plant or if special requirements are needed. It can be done.
Technically-qualified and competent management, especially including a chemist and/or chemical engineer, is critical in the development and implementation of a safety management system. Issues of compatibility and reactivity are often the most complex factors that will need to be taken into account in blending, processing and storing AFRs. The lack of experienced and educated oversight and management of these operations has often been a causative factor in the types of incidents that need to be avoided.
As a cement plant manager, AFR manager or corporate manager what key lessons are there to be learnt from this?
1. Find and retain management personnel and/or consultants who are technically qualified to assess the chemical and chemical engineering aspects of the plant’s process and of any incoming material.
2. Develop and implement a formal safety management system. Too often I hear from managers that because 'we are already doing all that stuff' they don’t feel a need to develop the formal written system. Such a statement demonstrates a significant misunderstanding of the issues involved.
Consider using one of the internationally-accepted formats such as the British Standard OHSAS 18001.8 One of the most critical aspects in determining the success of such a system is the involvement of employees from all levels from within the organisation. A system written by an outside consultant or by a corporate safety manager is unlikely to take into account the full range of issues that are needed to protect workers in plants on a day-in/day-out basis.
Furthermore, most outside consultants who might have extensive experience with safety management systems in typical plant operations are unlikely to be familiar with the range of issues that can arise from AFR operations.
3. Develop multiple layers of safety. Do not be one mistake away from a fatal accident. SOPs, engineering controls, quality control testing 9,10,11 and PPE are all different and critical layers in a good safety management system. PPE by itself is never the complete answer to the need to protect people.
4. Finally, investigate close calls just as vigorously as injuries or fatalities. It is hard to find an operation that does not attempt to understand why an injury or fatality occurred. They naturally want to prevent the recurrence. Yet during these investigations GCI often finds that there have been prior close calls.
Alternative fuel and raw materials present enormous opportunities for the cement industry to lower costs and improve sustainability.
Nevertheless, there are recognised and often unrecognised hazards that accompany such programmes. A properly-developed and well-run safety management system can mitigate these risks and often produce unanticipated benefits in operating cost reductions and improved efficiencies. As one performs the market research and technical reviews needed to initiate a profitable AFR programme, one should not forget the quality control and safety management systems that need to be developed in parallel with efforts to ‘trial’ that new AFR opportunity.
1 GOSSMAN, D (2013) 'Cement Kiln Engineered Fuel Patents and Sharps PELLA-DRX TM', in: GCI Tech Notes, 18, (1), Feb. Accessed: www.gcisolutions.com
2 ASTM INTERNATIONAL (2003) ASTM Standard D5928, 1996 (2003) Standard Test Method for Screening of Waste for Radioactivity. ASTM International: West Conshohocken, PA. DOI: 10.1520/D5928-96R10E)E01. Accessed: www.astm.org
3 GOSSMAN, D AND PEDERSEN, B (1996) 'Radioactive Waste Rejection Action Plan' in: GCI Tech Notes, 2, (3), March. Accessed: www.gcisolutions.com
4 US EPA (2000) Prevention of Reactive Chemical Explosions, Case Study: Waste Fuel/Oxidizer Reaction Hazards. US EPA – Office of Solid Waste and Emergency Response. EPA 550-F00-001, Apr Accessed: www.epa.gov/ceppo/
5 HEINLEIN, R (1940) 'Blowups Happen' in: Astounding Science Fiction, September.
6 US EPA (2000) Prevention of Reactive Chemical Explosions, Case Study: Waste Fuel/Oxidizer Reaction Hazards. US EPA – Office of Solid Waste and Emergency Response. EPA 550-F00-001, Apr Accessed: www.epa.gov/ceppo/
7 GOSSMAN, D (1998) 'HAZOP Reviews', in: GCI Tech Notes, 4, (8), Aug. Accessed: www.gcisolutions.com
8 BRITISH STANDARD INSTITUTION (2007) BS OHSAS 18001:2007 'Occupational Health and Safety Management System. Requirements. Jul.
9 GOSSMAN, D (2003) 'The ‘Best’ Referenced Methods for Organic Hazardous Waste Analysis – An Update' in: GCI Tech Notes, 8, (6), Jun. Accessed: www.gcisolutions.com
10 GOSSMAN, D (1993) 'A Method for the Rapid Semi-Quantitative Identification of Hazardous Organic Constituents in Liquid Organic Hazardous Waste Streams' in: Proceedings of the 1993 A&WMA Int Symposium on Waste Combustion in Boilers and Industrial Furnaces, SP-86, Air & Waste Management Association, Pittsburgh, PA, Mar.
11 GOSSMAN, D (1999) 'Data Quality Objectives at Resource Recovery Act Treatment, Storage and Disposal Facilities (DQOs at RCRA TSDFs)' in: Hazardous Waste Combustors Proceedings of a Specialty Conference, VIP-92, Air & Waste Management Association, Dallas, TX, 22-24 Sept.
Article first published in International Cement Review, July 2013.