Chris Macey of Resco Refractory Products, as IEEE-IAS CIC chair, welcomed all delegates to the 61st IEEE-IAS/PCA, especially the 300 first-time attendees. Chris gave a clear warning to all delegates to avoid any behaviour that could be interpreted as ‘anti-competitive.’ Corinne Fields of Refratechnik, conference organising committee chair, introduced the conference and pointed out that the event is organised by a large team of dedicated volunteers, backed-up by the professionals at World Class Events. Corinne introduced Nate Murphy of FLSmidth, CIC vice chair, who introduced the nearly-50 papers that were to be given at the event, and who, in turn, introduced LeRoy Stromberg, keynote speaker, chief construction officer of the Alberici Construction Group.
LeRoy Stromberg firstly introduced the Alberici group, a diversified engineering group which was involved in the construction of the LafargeHolcim Ste Genevieve cement plant. He commended the cement industry for taking the lead on safe working, saying that it is easier working with a supplier that insists on safe working practices. LeRoy pointed out that safe working is good business and stated that his company has run for 20 million hours without a lost time injury. Advances in construction that he mentioned include 3D models of new construction and laser-scans of either existing or newly-built concrete construction. Preconstruction offsite of as many components as possible has been a major shift in working practices, leading to increased safety, higher quality and cost reductions.
Robert McCaffrey, editorial director of Global Cement Magazine, gave the next presentation, on his vision of the cement industry in 2050. Full details were included in the May 2019 issue of Global Cement Magazine.
John Goetz, former plant manager of Ste Genevieve plant, next introduced the plant, which was the destination of the conference field trip. He reminded delegates that when it was built it was the world’s largest cement plant and is capable of shipping 20,000t of cement per day. The plant has achieved over 1100 days since the last lost time accident. It has achieved a world record of 14,500t/day of clinker, and achieved a feed rate of 1000t/ hr of feed into the kiln, sustained over 40 hours. The plant was the number one rated plant in LafargeHolcim in 2018, based on efficiency, cost and sustainability.
The conference operates parallel sessions, so our review includes only a selection of papers. John Kline started off the technical presentations at the conference and explained how to get the most out of the plant’s expert control system. John’s essential message was that the clinker production process is exceptionally complicated. A knowledge-base is required, but an ‘inference engine,’ must be used to interpret incoming data and to act upon it. Kiln feed consistency makes an expert control system’s job a lot easier and allows continuous efficiency improvement.
Greg Davis of Profi-Vision, Inc. next presented on control system evolution. He suggested that new hires from engineering schools are not going to be prepared to deal with antiquated technology, but instead will insist on adding value using more modern and sophisticated control systems (otherwise they will, sooner rather than later, walk out the door). Greg reiterated that cyber-security will become ever-more-important as cement plants become progressively dependent on software and control systems.
Steve Coppinger of CalPortland explained how his company is tracking down potential energy efficiency improvements, using ‘treasure hunts,’ and a company-wide ‘Energy Cup.’ Steve suggested that the least energy-efficient piece of equipment in any cement plant will probably be the compressors for production of compressed air, making them a focus for improvements. The Mojave plant has 3MW of ‘behind the meter’ (private) dedicated wind power, helping CalPortland win the EPA Energy Star Partner of the Year award for 14 years in a row. The Energy Star programme has helped the company save US$113m since 2004.
Mary Beth Kramer of Kramer Consulting, in answer to a question in the environmental session, made the point that cement companies do not need to ‘over-post’ on social media: she suggested that posting news ‘once a fortnight or month’ is enough.
An interesting session on how to create a sustainable workforce in the cement industry gave rise to a number of useful points, including, from Frank LaRosa of BWF Envirotec, that employees can expect some basics from a job, including personal growth (including training and engagement), stability and, crucially, safety. Dennis Johnson of US Minerals said that any safety programme is only as good as the weakest employee. Shane Wilson of ZAP Engineering pointed out that employees most highly value training and development, flexible hours, cash bonuses, healthcare, pension contributions and vacation allocations - in that order of importance. Patrick Hoffman of Cemex tells his colleagues to look for the aspect of any situation that could hurt them, but also pointed out that, after eliminating the rest of the risk from an operation, “PPE is the last resort.” Dennis Johnson, after exhorting delegates to learn something new every day, reminded his listeners that “If it can’t be grown, it must be mined.”
John Kline next asked, ‘What’s up with vertical mill drives?’ New mill drives are now approaching 12MW and many larger mills are now capable of grinding over 500t/hr, partly because mill production increases with the square of the table radius. Planetary gear boxes have become more popular in the last 20 years, since they help to balance the bed load of a vertical roller mill. Modern mills may have multiple drive arrangements, with perhaps four or six motors and drives powering the table. Gears integrating a motor are now coming into operation, although John Kline was somewhat sceptical of their design advantages. Spare gear boxes are sometimes made available in a group, or between companies cooperating together, in case of a gear failure. Failures occur most often if the drive has been operated beyond its design limits, or, often, if there has been a failure in the lubrication system. “Filter everything, trust no-one!” said John, with regards to lubricant fluid quality. Efforts should also be made to ensure that the table has an even load, that the pressure applied by the rollers is equal and that the feed chute is exactly in the middle of the table. Crucially, the longer the installed gearbox runs, the more important is the maintenance of any
spare gearbox.
In the General Practices session, Dominik Aufderheide of Di Matteo described an holistic approach to using alternative fuels for cement manufacture. Dominik pointed out that the German alternative fuel thermal substitution rate (TSR) is now 66%, a level that should be attainable in every country worldwide. Combustion must be understood before it can be optimised. The process starts with dehydration of the fuel particle, proceeds through pyrolysis, then to particle ignition and burnout and then finally to an ash or char stage, when the ash is incorporated into the clinker. The complete characterisation of alternative fuels particles is vital, to be able to ensure that all particles will be able to go through all stages of combustion without causing problems to pyroprocessing. Disagglomeration of alternative fuel particles may be important to ensure proper burn out. Dominik mentioned a modular and mobile AF receiving station that can be used as a ‘starter kit’ for companies wishing to start to use alternative fuels.
Tahir Abbas of Cinar Ltd next spoke about ‘A calciner at its best,’ specifically the design of the calciner at the Ste Genevieve plant. A mineral-interaction CFD model was used to optimise the design of the calciner, leading to a patent for the preheater, creating ultra-low NOx and low CO. High fuel burnout, fuel flexibility and zero hotspots were the other requisites for the calciner. Through modeling, the geometry of the calciner was optimised, to reduce stratification, to improve fuel mixing and to ensure near 100% fuel burnout. Carbon volatiles can be used to reduce the CO and NOx, and the production of the volatiles was a crucial design parameter to achieve low design emissions.
Gerard Lynskey of SSI Consulting spoke on optimisation of homogenising silos. Generally the older flat-bottom and more squat homogenising silos use very high pressure air to aerate the material and to effect mixing, to produce a more homogeneous feed for clinker production. Newer blending silos tend to be more slender and to use lower-pressure air, which tends to be less expensive, and to use an inverted cone for material extraction. The homogenising process with high pressure air tends to push the silo walls outwards, while in a blending silo the creation of a flow channel tends to pull the walls inwards. The design engineers must take these differences into account when designing the silos.
John Kline of Kline Consulting next asked “Can safety be the master measure?” The top 10 leading causes of workplace injuries are, in order of prevalence, overexertion, falls on the same level, falls to lower levels, being struck by an object or equipment, other exertions or bodily reactions, roadway accidents involving motorised land vehicles, being caught or compressed by equipment or objects, being hit by an object, and repetitive motions causing injury. John went on to give his listeners many nuggets of safety advice, mined from his time managing safety at 125 cement plants across the Lafarge group. Safety must be designed into your plant, and hazards must be designed out, while ‘near-misses’ must be closely examined. Employees should take responsibility for their own safety, but at the same time, they must have the authority and ability to stop unsafe work whenever and wherever it takes place. Encourage and reward safe behaviours, and promote procedural justice. A dirty plant is an unsafe plant, with many costs being incurred. Not least, a dirty plant has a negative effect on staff morale.
Second day
On the second day of the conference, Tom Beck, chairman of the US Portland Cement Association and CEO of Continental Cement, shared the current concerns of the association. “Now that the spotlight of public opinion is on us, it’s even more important for us to tell the good news story about cement.” Tom affirmed that the sector would prefer a cap and trade carbon permitting scheme, similar to the EU ETS, rather than a straight carbon tax. Tom suggested that a perhaps $2tn infrastructure bill may be coming down the legislative pipeline in the US, which would be great news for all participants in the industry.
Franz Ulm, professor at MIT’s Concrete Sustainability Hub, said that US roads have a significant and increasing need for rehabilitation, with one mile in five being considered in poor condition. Franz suggested that the inbuilt accelerometer in smart phones can be used to determine surface roughness of highways. An app, ‘Carbin,’ can automatically log this ‘roughness’ information and then sends it in anonymised form through to a central server, which it is then analysed. Widespread use of the app could quickly map the entire US road network. As is widely known, concrete roads, due to their stiffness, promote fuel efficiency of vehicles driving upon them, compared to asphalt roads and this can be seen in the collected data. The app can be downloaded from fixmyroad.us.
John Kline was next up (again), speaking about how the cement industry is addressing questions about its production of CO2. He pointed out that the cement industry has three main levers to address the issue, including increased use of supplementary cementitious materials, alternative fuels and novel cements. John gave examples of many different ways to sequester carbon dioxide, among them the production of new building materials. His presentation is available for download from www.cement2050.com.
The PCA’s chief economist, Ed Sullivan, next gave his traditional cement market outlook. He gave vent to his frustration at the still-outstanding infrastructure bill and stated that the economy will likely see a period of lower growth in the next couple of years. However, he suggested that the potential for a near-term recession is low - about a 20% chance of a recession within 12 months. This is despite the now-‘elderly’ 118-month-long current economic growth trend in the US, which is ongoing albeit at a modest rate of growth. Ed forecast continued low interest rates, and only very modest increases for the next three years. However, states are now seeing the growth of deficits in budgets, due to continued growth in entitlements. This may mean that spending may have to switch away from infrastructure spending. He reminded delegates that the US took the time from George Washington to the end of the presidency of Ronald Reagan to build its first trillion dollars of debt. Now the country increases its borrowings by one trillion dollars every year, totalling US$25tn in 2019. Servicing the national debt is not currently an issue, but an economic downturn could bring problems. Ed suggested that the southeast and west of the country will continue to see the strongest growth in cement demand.
Kirk McDonald of CalPortland Cement next spoke on the merits of Portland-Limestone cements (PLC), which in the US are now allowed to contain 5 - 15% of limestone content (with the limestone required to consist of at least 70% CaCO3). Around 25% of the European market is PLC, containing up to 35% limestone content. Kirk pointed out that limestone addition increases compressive strength up to around 12% addition, partly due to improved particle packing and particle size distribution, due to the creation on the limestone particles of nucleation sites for crystal growth, and to a lesser extent some chemical reactions. Around 20 plants now produce PLC in the US, making around 800,000t per year. The potential for PLC in the US is obviously huge, but the markets so far seem hesitant about widespread use of this lower CO2 cement.
Jeff Smith of Carbonfree Chemicals spoke about a facility in San Antonio, Texas, which operates the patented ‘Skymine’ technology in a commercial CCU facility to directly utilise cement kiln flue gas - without purification - to produce sodium bicarbonate, baking soda, at a profit. The unit, located next to the Nacodoches cement plant, consists of two separate parts: a traditional chlor-alkali unit and a carbon capture unit. The cement plant flue gas contains 12 - 15% CO2, with some trace metals and sulphur compounds and after CO2 extraction, the flue gas is returned to the cement plant. Rock salt (NaCl) brine is used in the process as a source of sodium, and as well as baking soda, the process creates hydrochloride acid, bleach and caustic soda. The plant captures around 75,000t/year of CO2, equal to removing 44,800 cars from the road for a year. The sodium carbonate produced represents around 10 - 15% of the US market demand and is sold into the fracking industry. It costs US$40-70/t to capture the CO2, with any future plant construction costs ranging from US$50 - 200m, depending on proximity to a cement plant and source of rock salt.
Rick Bohan of the US PCA next gave some details of CO2 capture technologies. Algae growth for CO2 capture is now at an advanced stage of development. Indirect heating through flash calcination, such as at HeidelbergCement’s Lixhe plant, is now under industrial-scale testing. Oxyfuel combustion allows the production of near-pure CO2, but the relatively high cost of the next stage of industrial testing is delaying the next steps. Amine absorption is a well-known technology, already used in other industries, which is due to be tested at the HeidelbergCement Norcem Brevik plant through 2019, potentially capturing in the region of 400,000t of CO2 per year. Calcium looping is another option for carbon capture and is due to be tested within the next 18 months. Cemcap and ECRA have both written reports on the economics of these and other technologies. Certainly, the cement industry is active in the area of carbon emission avoidance and/or abatement, in order to prepare itself for the future carbon-constrained world.
Xavier D’Hubert, senior consultant at XDH, gave a presentation on micro-grids for the cement industry. He stated that the current energy transition is proceeding along three fronts: decarbonation of energy generation, electrification of industrial processes and decentralisation of energy generation and storage. The cement industry is a large user of electrical energy, is a large CO2 emitter and is also a major source of waste heat energy - making it a prime target for load-switching, local energy generation, energy storage and localised energy grids. Xavier pointed out that daily electrical use/renewable energy generation trends (known as the ‘Californian duck’ or ‘Texan dead armadillo’ curves), would benefit the cement industry by allowing it to store energy during the sunny daylight hours when energy is relatively cheap, using pump-storage, flywheels, compressed-air systems, Li-ion, flow or 3D-printed batteries, and to use it for process requirements (such as grinding) at night. Xavier went further and suggested that the cement industry could even become hydrogen-powered, with hydrogen as the main fuel, and with electricity generated from hydrogen fuel cells.
The next IEEE-IAS/PCA conference will take place in Las Vegas on 19 - 23 April 2020.