crushed stone aggregates - lehigh hanson, inc

crushed stone aggregates - lehigh hanson, inc

Production of crushed stone has three stages: Primary crushing to break down the stone to a manageable size; secondary and tertiary crushing to render the rocks into sizes specific to their applications; and screening to separate the crushed stone for further processing or for finished products sizes.

Coarse aggregates consist of gravel, crushed stone or recycled concrete with particle sizes of ranging from 3/8-inch to 1.5 inches. Coarse aggregates are used in a wide range of construction applications, notably in concrete and asphalt mixes.

Common uses for base coarse crushed stone Foundation for asphalt pavement Foundation for concrete pads and pavements Unpaved roads and shoulders Backfill for pipe and underground utilities Cement-treated base

Sizes and Designations Sizes and designations vary by location due to governing agency requirements. Common designations include, but are not limited to: Base, Subbase, Dense Graded Base, -Crushed Stone Base, Graded Aggregate Base (GAB), Aggregate Base Coarse(ABC), Macadam Base Coarse (MBC)

Large coarse aggregates that consist of crushed stone (hardstone such as rhyolite, granite and sometimes dolomite) with particle sizes ranging from 1 inches to 4 inches. Typical uses include construction applications and railroad ballast.

Common Uses Agricultural lime agent to treat soil (Ag-lime) Mineral filler or fine grind, currently available from Hanson at Thornton IL, Nokomis IL, Plum Run OH, Sandusky OH, or Watertown NY. Landscaping stones Skid resistance on ice or snow Chemical stone Scrubber stone to treat flue gases Filter courses for septic systems

john's hall aggregates, jamaica (west indies) :: the suitability of limestone aggregates for use in structural concrete

john's hall aggregates, jamaica (west indies) :: the suitability of limestone aggregates for use in structural concrete

The following is an excerpt of a presentation made by Mr. Gordon Hutchinson at a seminar hosted by John's Hall Aggregates Limited entitled "The future of Construction Aggregates" held on June 13, 2012 at the Lecture Theatre, Montego-Bay Community College.

Aggregate generally used in most applications is comprised of a combination of several particle sizes with particles larger than 4.75 mm (3/16") referred to as Coarse Aggregate. Coarse aggregate range in particle sizes up to 75mm. When several particle sizes are present, the aggregate is said to be Graded. When only one size is present, it is called Single-sized. Particle size is determined by the size of the opening in a square mesh (Sieve) through which that particle can just pass.

Fine aggregate is made up of particle sizes smaller than 4.75mm (3/16") and extends down to sizes smaller than 0.075mm (#200 mesh). In concrete generally and, to a lesser extent in asphaltic concrete, the proportion of minus #200 mesh sizes is normally limited to just a few percent of the total mass of aggregate. Excessive fines (Minus #200 mesh sizes) can have unfavourable influence on the quality of the overall composite material. Influence of Aggregates on Properties of Composite Material Aggregate makes up between 70 - 80 percent of the volume of Concrete and 80 to 88 percent of the volume of Asphaltic Concrete. Understandably, the properties of the aggregate exert considerable influence on the properties of the composite material of which it is a constituent. Strength of the aggregate component may determine the highest compressive strength of hardened concrete. ASTM and most specifications, however, state only that the aggregate shall consist of "hard, strong, durable" particles. Weak aggregate is not acceptable and should not be used where strength of concrete is a primary requirement. It is therefore important to use only aggregate produced from strong limestone (good compressive strength). Testing the compressive strength of the aggregate particles is not normally carried out to determine its strength or suitability. This property is normally determined by a simpler method such as the Aggregate Crushing Value (ACV) or the Los Angeles Abrasion test which also gives a measure of the abrasion resistance and "toughness" of the aggregate. Limestone Aggregate in Concrete Hard durable limestone aggregate is capable of producing concrete of medium compressive strength as is used in normal structural applications. In Jamaica, we have designed and tested concrete mixes with specified strengths up to 35 MPa (5000 psi) Cube Strength. Higher strengths are attainable but one must check and ensure that, given the wide range of strength of our limestones, the material being used is not of the weaker varieties. Because limestone aggregate is normally comprised of 100% crushed fragments, the better surface texture and higher angularity that obtains lead to good bond with the cement and good particle interlock, both of which help in achieving good compressive strength properties. Our general experience with concrete made with limestone aggregates has indicated that somewhat lower cement contents are required than with local river stone aggregates. Limestone Aggregate in Asphaltic Concrete Limestone aggregate is also generally suitable for use in Asphaltic Concrete and is economically feasible when the absorption is relatively low (Less than 2.5%). High absorption rates may result in added asphalt binder needed to allow for asphalt absorbed by the aggregate. However, if used in a wearing surface, limestone aggregate has a tendency to polish thus reducing the skid-resistance of the pavement over time. Dolomitic limestones are generally preferred in asphaltic concrete wearing courses since they are generally harder and tend to polish less, thus maintaining their skid-resistance properties longer. Dolomitic limestones also have lower absorption rates and thus lead to use of lower Bitumen Content in asphaltic concrete mixes. Crushed, Washed Limestone Sand Unfortunately, not many aggregate producers have bothered to produce Limestone sand for the general construction history. As a result, there is not a considerable amount of performance data or history of the use of Limestone Sand in local construction. Crushing Limestone to produce fine aggregate results in the generation of a substantial amount of fine sizes (minus 0.075mm or #200 mesh) commonly referred to as dust. These fines do not aid in the production of good quality concrete and therefore must be removed from the sand before combining with Coarse Aggregate and cement. The cost of separating the dust tends to militate against the economical production of limestone sand. However, Limestone sand meeting standard grading specifications for concrete can be effectively and economically used to produce good quality concrete with concrete properties comparable to mixes made with our local igneous source sands. Examples of the use of Limestone sand in local projects include Riu Hotel in Negril and the Montego Bay Sports Stadium at Catherine Hall. Structures Built with Limestone Aggregate Concrete Limestone is one of the most common rock types in the world and is widely exploited for use in construction. Because of its range of physical properties, it is easily adapted to use in a variety of structural and architectural applications. In the United States of America and Europe Limestone has been used extensively in building construction and has demonstrated excellent durability to normal weathering. Except for its susceptibility to degradation is environments where acid is present, it is a tried and proven building material. In Florida, USA where only Limestone is present, it is used extensively in all types of construction and to a considerable extent in concrete as well as in road and airport base and sub-base construction. Conclusion Limestone is the most commonly and extensively mined rock in Jamaica as in many other countries around the world. Its use in structural concrete has not developed in keeping with the growth of our construction industry but has been limited mainly because of the previously easy availability of sand and gravel from our river sources. Locally available Limestone, although variable in quality and physical properties, can by appropriate mining and processing be used in almost all other applications where igneous river source aggregate has previously been used. The critical steps necessary for greater utilization of limestone in construction in Jamaica should include: Identifying all potential sources of construction quality limestone across the island. Preparing an inventory of our limestone reserves appropriately graded and cataloged in respect to quality and physical properties relevant to the various uses and applications. Education and training of aggregate producers in the technology of aggregate production to meet standard specifications. Education of the consumers and potential consumers of construction aggregates on the use of limestone and the economics of using limestone in construction. Acknowledgements Data Research - Kayanna Bromfield, BSc. QA/Laboratory Administrator, JETS Laboratories Limited 2018 John's Hall Aggregates

Influence of Aggregates on Properties of Composite Material Aggregate makes up between 70 - 80 percent of the volume of Concrete and 80 to 88 percent of the volume of Asphaltic Concrete. Understandably, the properties of the aggregate exert considerable influence on the properties of the composite material of which it is a constituent. Strength of the aggregate component may determine the highest compressive strength of hardened concrete. ASTM and most specifications, however, state only that the aggregate shall consist of "hard, strong, durable" particles. Weak aggregate is not acceptable and should not be used where strength of concrete is a primary requirement. It is therefore important to use only aggregate produced from strong limestone (good compressive strength). Testing the compressive strength of the aggregate particles is not normally carried out to determine its strength or suitability. This property is normally determined by a simpler method such as the Aggregate Crushing Value (ACV) or the Los Angeles Abrasion test which also gives a measure of the abrasion resistance and "toughness" of the aggregate. Limestone Aggregate in Concrete Hard durable limestone aggregate is capable of producing concrete of medium compressive strength as is used in normal structural applications. In Jamaica, we have designed and tested concrete mixes with specified strengths up to 35 MPa (5000 psi) Cube Strength. Higher strengths are attainable but one must check and ensure that, given the wide range of strength of our limestones, the material being used is not of the weaker varieties. Because limestone aggregate is normally comprised of 100% crushed fragments, the better surface texture and higher angularity that obtains lead to good bond with the cement and good particle interlock, both of which help in achieving good compressive strength properties. Our general experience with concrete made with limestone aggregates has indicated that somewhat lower cement contents are required than with local river stone aggregates. Limestone Aggregate in Asphaltic Concrete Limestone aggregate is also generally suitable for use in Asphaltic Concrete and is economically feasible when the absorption is relatively low (Less than 2.5%). High absorption rates may result in added asphalt binder needed to allow for asphalt absorbed by the aggregate. However, if used in a wearing surface, limestone aggregate has a tendency to polish thus reducing the skid-resistance of the pavement over time. Dolomitic limestones are generally preferred in asphaltic concrete wearing courses since they are generally harder and tend to polish less, thus maintaining their skid-resistance properties longer. Dolomitic limestones also have lower absorption rates and thus lead to use of lower Bitumen Content in asphaltic concrete mixes. Crushed, Washed Limestone Sand Unfortunately, not many aggregate producers have bothered to produce Limestone sand for the general construction history. As a result, there is not a considerable amount of performance data or history of the use of Limestone Sand in local construction. Crushing Limestone to produce fine aggregate results in the generation of a substantial amount of fine sizes (minus 0.075mm or #200 mesh) commonly referred to as dust. These fines do not aid in the production of good quality concrete and therefore must be removed from the sand before combining with Coarse Aggregate and cement. The cost of separating the dust tends to militate against the economical production of limestone sand. However, Limestone sand meeting standard grading specifications for concrete can be effectively and economically used to produce good quality concrete with concrete properties comparable to mixes made with our local igneous source sands. Examples of the use of Limestone sand in local projects include Riu Hotel in Negril and the Montego Bay Sports Stadium at Catherine Hall. Structures Built with Limestone Aggregate Concrete Limestone is one of the most common rock types in the world and is widely exploited for use in construction. Because of its range of physical properties, it is easily adapted to use in a variety of structural and architectural applications. In the United States of America and Europe Limestone has been used extensively in building construction and has demonstrated excellent durability to normal weathering. Except for its susceptibility to degradation is environments where acid is present, it is a tried and proven building material. In Florida, USA where only Limestone is present, it is used extensively in all types of construction and to a considerable extent in concrete as well as in road and airport base and sub-base construction. Conclusion Limestone is the most commonly and extensively mined rock in Jamaica as in many other countries around the world. Its use in structural concrete has not developed in keeping with the growth of our construction industry but has been limited mainly because of the previously easy availability of sand and gravel from our river sources. Locally available Limestone, although variable in quality and physical properties, can by appropriate mining and processing be used in almost all other applications where igneous river source aggregate has previously been used. The critical steps necessary for greater utilization of limestone in construction in Jamaica should include: Identifying all potential sources of construction quality limestone across the island. Preparing an inventory of our limestone reserves appropriately graded and cataloged in respect to quality and physical properties relevant to the various uses and applications. Education and training of aggregate producers in the technology of aggregate production to meet standard specifications. Education of the consumers and potential consumers of construction aggregates on the use of limestone and the economics of using limestone in construction. Acknowledgements Data Research - Kayanna Bromfield, BSc. QA/Laboratory Administrator, JETS Laboratories Limited 2018 John's Hall Aggregates

Aggregate makes up between 70 - 80 percent of the volume of Concrete and 80 to 88 percent of the volume of Asphaltic Concrete. Understandably, the properties of the aggregate exert considerable influence on the properties of the composite material of which it is a constituent. Strength of the aggregate component may determine the highest compressive strength of hardened concrete. ASTM and most specifications, however, state only that the aggregate shall consist of "hard, strong, durable" particles. Weak aggregate is not acceptable and should not be used where strength of concrete is a primary requirement. It is therefore important to use only aggregate produced from strong limestone (good compressive strength). Testing the compressive strength of the aggregate particles is not normally carried out to determine its strength or suitability. This property is normally determined by a simpler method such as the Aggregate Crushing Value (ACV) or the Los Angeles Abrasion test which also gives a measure of the abrasion resistance and "toughness" of the aggregate.

Hard durable limestone aggregate is capable of producing concrete of medium compressive strength as is used in normal structural applications. In Jamaica, we have designed and tested concrete mixes with specified strengths up to 35 MPa (5000 psi) Cube Strength. Higher strengths are attainable but one must check and ensure that, given the wide range of strength of our limestones, the material being used is not of the weaker varieties.

Because limestone aggregate is normally comprised of 100% crushed fragments, the better surface texture and higher angularity that obtains lead to good bond with the cement and good particle interlock, both of which help in achieving good compressive strength properties. Our general experience with concrete made with limestone aggregates has indicated that somewhat lower cement contents are required than with local river stone aggregates.

Limestone aggregate is also generally suitable for use in Asphaltic Concrete and is economically feasible when the absorption is relatively low (Less than 2.5%). High absorption rates may result in added asphalt binder needed to allow for asphalt absorbed by the aggregate. However, if used in a wearing surface, limestone aggregate has a tendency to polish thus reducing the skid-resistance of the pavement over time. Dolomitic limestones are generally preferred in asphaltic concrete wearing courses since they are generally harder and tend to polish less, thus maintaining their skid-resistance properties longer. Dolomitic limestones also have lower absorption rates and thus lead to use of lower Bitumen Content in asphaltic concrete mixes.

Unfortunately, not many aggregate producers have bothered to produce Limestone sand for the general construction history. As a result, there is not a considerable amount of performance data or history of the use of Limestone Sand in local construction. Crushing Limestone to produce fine aggregate results in the generation of a substantial amount of fine sizes (minus 0.075mm or #200 mesh) commonly referred to as dust. These fines do not aid in the production of good quality concrete and therefore must be removed from the sand before combining with Coarse Aggregate and cement. The cost of separating the dust tends to militate against the economical production of limestone sand.

However, Limestone sand meeting standard grading specifications for concrete can be effectively and economically used to produce good quality concrete with concrete properties comparable to mixes made with our local igneous source sands.

Limestone is one of the most common rock types in the world and is widely exploited for use in construction. Because of its range of physical properties, it is easily adapted to use in a variety of structural and architectural applications.

In the United States of America and Europe Limestone has been used extensively in building construction and has demonstrated excellent durability to normal weathering. Except for its susceptibility to degradation is environments where acid is present, it is a tried and proven building material. In Florida, USA where only Limestone is present, it is used extensively in all types of construction and to a considerable extent in concrete as well as in road and airport base and sub-base construction.

Limestone is the most commonly and extensively mined rock in Jamaica as in many other countries around the world. Its use in structural concrete has not developed in keeping with the growth of our construction industry but has been limited mainly because of the previously easy availability of sand and gravel from our river sources. Locally available Limestone, although variable in quality and physical properties, can by appropriate mining and processing be used in almost all other applications where igneous river source aggregate has previously been used. The critical steps necessary for greater utilization of limestone in construction in Jamaica should include: Identifying all potential sources of construction quality limestone across the island. Preparing an inventory of our limestone reserves appropriately graded and cataloged in respect to quality and physical properties relevant to the various uses and applications. Education and training of aggregate producers in the technology of aggregate production to meet standard specifications. Education of the consumers and potential consumers of construction aggregates on the use of limestone and the economics of using limestone in construction. Acknowledgements Data Research - Kayanna Bromfield, BSc. QA/Laboratory Administrator, JETS Laboratories Limited 2018 John's Hall Aggregates

The critical steps necessary for greater utilization of limestone in construction in Jamaica should include: Identifying all potential sources of construction quality limestone across the island. Preparing an inventory of our limestone reserves appropriately graded and cataloged in respect to quality and physical properties relevant to the various uses and applications. Education and training of aggregate producers in the technology of aggregate production to meet standard specifications. Education of the consumers and potential consumers of construction aggregates on the use of limestone and the economics of using limestone in construction. Acknowledgements Data Research - Kayanna Bromfield, BSc. QA/Laboratory Administrator, JETS Laboratories Limited 2018 John's Hall Aggregates

The critical steps necessary for greater utilization of limestone in construction in Jamaica should include: Identifying all potential sources of construction quality limestone across the island. Preparing an inventory of our limestone reserves appropriately graded and cataloged in respect to quality and physical properties relevant to the various uses and applications. Education and training of aggregate producers in the technology of aggregate production to meet standard specifications. Education of the consumers and potential consumers of construction aggregates on the use of limestone and the economics of using limestone in construction. Acknowledgements Data Research - Kayanna Bromfield, BSc. QA/Laboratory Administrator, JETS Laboratories Limited 2018 John's Hall Aggregates

plc: greener cement | home

plc: greener cement | home

Portland-limestone cement is engineered with a higher limestone content. PLC (Type IL) gives specifiers, architects, engineers, producers, and designers a greener way to execute any structure, paving, or geotech project, with virtually no modifications to mix design or placing procedures. All while maintaining the resilience and sustainability youve come to expect from portland cement concrete.

crushing limestone with reliability - efficient plant

crushing limestone with reliability - efficient plant

Tom French, site reliability process leader at Mississippi Lime in Ste. Genevieve, MO, is getting more sleep these days. Its a small pleasure that he counts among many other positive results to emerge from a multi-year, multi-faceted, reliability-improvement process he and his team helped put in place at this limestone-processing operation. Located 65 mi. south of St. Louis along the Mississippi River and perched over what is considered the largest limestone deposit in North America, the privately held company mines, crushes, and processes limestone onsite. It makes a variety of calcium-based products (see sidebar) and bags or bulk-loads them for distribution. The multi-shift, year-round operation is the towns largest employer and is celebrating its 108th year in business. With headquarters in St. Louis and facilities in several other states, Mississippi Lime is one of the nations top lime producers.

To appreciate the reliability improvements the company has made at Ste. Genevieve, its important to understand the scope of this operation. Conceptually, the process is simple: Limestone is blasted, drilled, scaled out, and crushed to various sizes (based on customer need) in a very large drive-in mine located directly beneath the plant and many acres surrounding it. It is then moved by conveyors out of the mine to kilns where it is heated in a process known as calcination, which drives off unwanted components. The resulting calcium-based productlimeis separated by particle size, then loaded into tractor-trailers or bulk-loaded into railcars or bulk-carrier trucks, barges, or bagged for delivery to customers around the world. While output and customer specifications are confidential, the entire process involves only three variables to meet any customer need: size of the crushed lime product, the amount of heat to which it is subjected, and the length of time it is heated.

The straightforwardness of this rough-and-tumble process is belied by the severe conditions under which it functions. The enormous outdoor kilns, for example, reach temperatures of 2,500 F, which keep most plant areas in a desert-like state year round. Furthermore, virtually all equipmentfrom scaler heads that are used to scrape limestone rock from mine walls, to Caterpillar loaders and dump trucks, to the crusher units, conveyors, and high-temperature kilnsis in constant contact with stone. The limestone mined here is not hard enough to be used for structural purposes, but still wreaks havoc with equipment. The demands of working under such conditions, essentially unchanged since the earliest days of limestone processing, had for years left little room to focus on anything else at Ste. Genevieve. Maintenance was a find and fix process, and reliability meant showing up and working hard.

We were really good at saving the day, said French, a 30-yr. Mississippi Lime veteran. Something could break in the middle of the night and they would fix it, and everyone was high-fiving the next day. They could hardly stay awake, but they saved whatever they saved, and that was the culture. We were fixers, not maintainers.

That approach might have persisted into the 21st century if not for two key factors: The uses and demand for lime were growing, and large numbers of longtime employees were reaching retirement age. By the early 2000s, Mississippi Lime was a textbook example of a company poised to rapidly lose a large segment of its institutional knowledge, according to site maintenance manager John Swafford. We are a premier place to work in this community, he said, which was both a good thing and a bad thing for us long term. The company did a lot of hiring in the 1970s, but when these workers started to retire after 40-plus years of service, and newer groups came in behind them, we had difficulty passing that knowledge along. And that has been the real driver for our reliability program.

In 2005, Mike Sheffield joined Mississippi Lime as an area plant manager and three years later assumed the role of general manager for the entire Ste. Genevieve site. His background included experience at a world-class chemical plant on the East Coast, which stood in stark contrast to what he saw in his new position. When I came here, it was 180-degrees from my previous job, he said. The plant had just started to put in new kiln technologies, but otherwise, you were looking at technology from the 50s, 60s, and 70s. It was like taking a very large step backwards in time. When I got acquainted and started looking at what [maintenance and reliability] systems we had in place, I saw that there werent any.

Fortunately, Sheffield and others in management recognized the severity of the double-edged problem the plant faced, and took steps to correct it. By this time, French had risen from production to a supervisory role and, along the way, learned about the plants four business units (distinguished by the sites key processes: mine, rotary kilns, vertical kilns, and packaging/distribution) and how each operated. While commissioning a new bagging facility that involved many long days of troubleshooting, and participating in a newly formed reliability team, French began to see his operation differently.

When asked to step into a reliability position in 2007, he jumped at the opportunity. One of his first reliability learning opportunities involved a critical piece of equipment that had been destroyed due to improper adjustment. The superintendent at the time cut that equipment in half to show everyone what the inside looked like and how the oil flowed. And when he did that, it was like somebody turned on a light bulb. From that point on, I was jacked up about everything we do regarding reliability.

By 2008, French was leading small groups of Mississippi Lime maintenance- and production-team members to maintenance-and-reliability conferences, and telling them to keep open minds about what they saw and heard. Some went with reluctance, having experienced previous efforts by consultants that often didnt click. It was a real cultural change for us to go from a large maintenance group that was good at what they did within their frame of reference to accepting new ideas and new people, said Swafford. In their world everything was working fine, but we had to get more competitive.

As the companys workforce and upper management evolved to meet new conditions, so did priorities. We began to talk about downtime, frequency, on-stream time, and how long it takes to fix things, said Swafford. We had to determine how to keep things running longer. With kilns running 24/7 like a power plant, Swafford noted that these units had the biggest influence on maintenance and reliability efforts. When a kiln is down, not only is production lost, so is heat. It can take a tremendous amount of energy to heat our processes back up before we make one ton of lime, said Swafford, so we guard that because its money we dont get back.

Swafford explained, How often you stop is the key. When we first started with our new kiln systems, we were doing work on them regularly. Today, our goal is to stretch our outages further and further using technologies like vibration analysis, oil analysis, thermography, and increased engineering focus. Were extending our outage duration too, which is also a big expense. Weve shrunk the length of those outages by 50%. We still have our fair share of firefighting, he said, adding that the team developed downtime Pareto charts to identify bad actors. We focus on the chart bars to the left, said Swafford. We pick one, solve it, and put it to bed.

This approacha TPM-style tactic that focused on overhauling all key equipmentwas tough, said Swafford. But when we look back now at some of the things that kept us up at night, we dont have to mess with that particular issue any more. This means fewer off-shift phone calls, and less getting up in the middle of the night.

Through improved maintenance and reliability systems, successes began adding up, which freed time to do more. And we poured it back into PMs and reliability, said Swafford. We started oil analysis for all of our critical equipment in the plant, and we started thermography because everything we do here is about heat. The refractory in our kilns, for example, is a high-dollar, high-wear item for us, so we need to know what it looks like. With infrared, we can identify issues much clearer inside and outside. We know where to focus our work, and it allows better decision making regarding the need to shut down or repair online.

Other tactics include ultrasound, being introduced now, along with the formation of a Reliability Council and an Operational Excellence team; a Reliability Pillar program that charts key data such as top maintenance costs and downtime; and pursuit of CMRP certification through the Society for Maintenance & Reliability Professionals (smrp.org). French became the first company employee to receive CMRP certification in 2008, and has since been joined by seven others, with three more scheduled to take the exam in October.

Though plant reliability and on-stream time were improving, attrition continued. In the first decade of the new millennium, close to half of the plants workforce retired. This pace has yet to slow, said Swafford, which is a downside because we lose years of valuable experience. But the upside now is that when we bring in a new person, all he hears and sees is our current reliability and maintenance process metrics and KPIs.

In 2007, an apprenticeship program was launched to ensure that new employees only saw the world-class tactics the company now embraced. For some, the apprenticeship includes a fully paid two- or three-year education at Ranken Technical College in St. Louis. We pay for their entire education going into the crafts, said Swafford. And at this school, you have to be there, you have to be dressed for work, and the courses are taught by people who have worked in industry. This training gives our guys core knowledge so they can be put on a pump anywhere in the plant, and figure it out. We still have to educate them on our specialized equipment and our work process, said Swafford, but this gives them a good head start.

Todays plant workforce differs significantly from that of a decade ago. Many aboard still have high years of service, but even this group has largely picked up on the importance of the companys focus on reliability. French offered several examples of employees who were given the opportunity to attend offsite conferences or participate in special training and were skeptical at first, but concluded afterward that the new ideas had merit. Now a respected mentor, Frenchs non-confrontational, work with me approach has helped many tenured workers accept new concepts. Our team members are becoming more involved and are proud of what theyre doing, he said. They know that were not just blowing smoke.

Sheffield said it didnt take long before he saw the impact of the apprenticeship program and the training initiatives. At one point, we solicited a company to come in and do our PMs, he said, but when they told me what it would cost, I said we could do these ourselves, and we did. Over time, our team members got better and better. We built a robust maintenance workflow process and implemented a very successful asset-management system. Our planners and schedulers got better, and weve built a really good system in the last three or four years.

The Mississippi Lime workforce at Ste. Genevieve has now reached a level equivalent to my previous experience, Sheffield added. Ive learned that you cant come into a plant and put a system in place by telling people this is what youre going to do. You come into a plant and you allow people to learn and develop the system so they know theyre a part of it. Thats what makes it last.

As maintenance crews improved their techniques, it became clear that operators needed to pick up the pace as well. Formal training for operators had never existed, said Sheffield. Instead, after receiving standard MSHA (Mine Safety and Health Administration) training, new employees were dispatched directly into the plant and assigned work. And if you ask people about those first weeks on the job, many will tell you it was scary, he said. This is a huge place, and its intimidating.

Today, a mentor takes all new employees through a training-heavy introductory period. Then we start them with the standard-work process, which we began in 2013, said Sheffield, noting that this provides new employees a step-by-step process to guide them through job tasks. If we hadnt gone down this path, he said, I hate to think what our safety performance would be, because thats our biggest concern. We have big equipment and when something bad happens, it can be pretty serious.

To develop the standard-work process, a design team was developed. We asked for hourly volunteers from production and maintenance to form a team that would work across the plant, interviewing operators about how they perform their tasks, and photograph each step, said French. Six were chosen to form what is now called the Standard Work Action Team or SWAT, and together they created a text-and-photo template that would accommodate the information they gathered.

The interview process was repeated as many times as there are operators for a given task, said French. If four guys did a particular job, we would interview all four, trying to gain consensus between all of them. Each would get to review the document we created before we published it. Then we had subject-matter experts, such as process engineers and supervisors, on a review/approval team. Once the operators agreed on how to perform the task, the approval team would go through the document to find any bad practices. They could tweak or modify the document to reflect how the job should be done.

The gathering process took a full year and represented about 17,000 man-hours of time. It produced 2,760 individual operating tasks to be catalogued, each of which now forms a one-page explanation of how and why that job is done. If we have a process that requires 5,000 particles of this and 6,000 particles of that, we dont want you to deviate from that, said French, but youll know why. All of this is in books and its online so it can be printed off for training. The group uses SharePoint software to manage standard work documents and permissions, support a calendar, and send announcements.

Members of the companys Reliability and Maintenance Pillar Teams include (left to right) John Swafford, site maintenance manager; Jeff Zerwig, maintenance supervisor; Tom French, site reliability process leader; Cecil Burney, maintenance manager; Nathan Hooper, operations team leader; George Hall, maintenance planner; and D.J. Steagall, operations manager.

As output and uptime continue to increase at Mississippi Lime, maintenance-and-reliability team members are keenly aware of the need to focus on on and move ahead with the programs theyve worked hard to implement. Our challenge is to maintain the progress weve made, said Swafford. But its all about the people. The better your selection of people, the better things will go. And the more people we get involved in the plant and our processes, the better our growth.

For Sheffield, the advances made at the plant since his arrival are unique in his experience. This isnt the first time Ive set up systems and worked through them, he said. Ive also been to a lot of seminars and Ive heard a lot of people talk about doing it, but around here were actually doing it. We dont talk that much about it, but its becoming part of our culture.

Confident he has the right people and programs to sustain their hard-won gains, French offered one more example of their attention to detail. Just this week were doing a job on our crushing system, he said, and even though we havent done much work on this equipment, we had the drawings with documents and procedures, and the history of what we had done. Real data! We have metrics now we didnt have before, and its an all-in type of thing. Its not just reliability, maintenance, engineering, or production; its a partnership that has paid off. It sometimes seems like were constantly going over what we were just teaching, he added, but you have to do that to sustain it. Were living proof that this is a journey.

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