Category: Improving efficiency (2 posts)
Like many other businesses, cement plants increasingly have to focus on short-term returns to the stock market. At the most basic level, profitability or lack thereof can be very simply correlated with two main factors: market dynamics and operational performance. Of course, these two are by no means distinct from each other – it’s certainly possible to be doing badly in a booming market! – but we’ll leave market dynamics for another day and concentrate on what we know best: plant performance.

Diagnosing problems early
The saying goes that prevention is better than a cure, but you can’t prevent much without careful monitoring. Basic process engineering measurements should be carried out on a frequent basis to ensure that all areas of the cement plant are performing in line with expectations. While this may seem like obvious advice to a cement producer, there is significant focus on equipment inspection from the mechanical and electrical perspective; process measurements are often forgotten until the plant is running poorly. Keeping the equipment running is one thing, but keeping it running efficiently is the key to low cost production.

Check your instruments
We rely so heavily on instrumentation to measure our plant operations, but how often do you check the instruments are properly calibrated? How often do we see plants with strange back end gas analyser readings what just aren’t possible – high O2 alongside high CO and SO2? But without checking and trying to understand what is wrong, the readings become the norm and the value of having that instrument becomes zero.

The lesson? If it looks wrong, it probably is wrong. Check your instrumentation regularly.

How often do you take stock checks?
You’d be surprised how often I’ve come across cement plants that don’t regularly check their stocks. Perhaps it’s almost too obvious and that’s why it gets forgotten, but balancing raw meal to clinker and cement stocks is essential, not just to profit margins but also to indicate that something is wrong in the process.

Financial projections are based on assumed quantities – kiln throughput, fuel consumption, etc. It’s worth checking both kiln tonnage and fuel consumption through a clinker weigh-off for 24 hours. Finding that you are using more fuel, or producing less clinker than expected can have a major impact on the company’s financials. A profit warning is never a good thing, but one based on simple accounting mistakes is particularly awful – and totally avoidable. Check and double-check your figures.

Examine trends as well as data
Every modern cement plant collects reams of data, but data without analysis is pointless. Use your data to track trends and you could discover and solve problems before they occur, turn plant performance around and avoid having to write that dreaded note to shareholders.

Plant data can be overwhelming and sometimes it’s hard to see the wood for the trees. If you’re struggling to pinpoint the source of a problem, give JAMCEM a call. A fresh pair of experienced eyes can be exactly what you need to identify where plant performance is falling short and how to fix it. Take a look at our references to see how we’ve helped numerous cement plants streamline their operations and improve productivity.
Understanding how to balance the cement production process for lower cost mode of operation  
Cutting costs doesn’t have to involve a huge system overhaul and it shouldn’t only be a directive from above. The responsibility for seeking out and implementing opportunities to reduce cost per tonne generally lies with the Process Engineer and the Production department. Here, I look at one of my preferred approaches to establishing the lowest cost mode of operation.

Do you know what efficient operation looks like?
Before you start on such a project, it’s worth reflecting on the basic parameters at the core of efficient operation. These are too often forgotten over time, as equipment ages and personnel get used to working around under-performance. Changes in the raw materials, fuels and final product specification also have an impact that needs to be borne in mind.

If you can answer the question ‘why isn’t this equipment operating efficiently’, you’re halfway to a solution, but in order to do this you need to first establish what efficient operation looks like for your plant. Read my previous post about performance analysis for more on this.

Balancing every stage of the process
Cement production is a delicate operation. Everything in this linear process needs to work well for the whole process to be truly efficient. Therefore, a good approach to identifying the lowest cost mode of operation is to ensure that the process parameters between each stage of the process are in balance.

Output: from quarry to kiln
This is the first parameter that most plants will have balanced. The quarry, crusher and raw mill output needs to produce sufficient feed at the right chemical and physical specification for the kiln to keep running at its optimum level. The balance between the kiln and cement mill is less important, since the clinker store acts as the natural buffer through seasonal variations in cement demand. However, the kiln must be capable of producing sufficient clinker to see the plant through the peak sales months or customers will be lost.

In new plants that have been well designed, the output should be balanced at the desired chemical and physical target parameters. But what happens as the plant ages? Or the raw materials change? Or the fuels change? The process becomes unbalanced.

Case study: ball mill
Let’s look at an example from a real plant. Over time, the ball mill output had been steadily decreasing, due to a lack of attention to the media grading and inleaking air around the circuit, which resulted in inadequate mill ventilation. The plant got to the stage where there was no overtaking capacity in the mill and therefore, to achieve the required mill output, the raw meal 90 micron residue was increased.
As the 90-micron residue was siliceous, the fuel consumption of the kiln increased, the kiln output dropped and the clinker was much harder burnt, which resulted in a knock-on effect in the cement quality.

This example shows how a lack of attention to process engineering and maintenance issues in the raw milling department created a chain of events that affected the whole process, including the final product quality. Examples like this are numerous and often include upratings, where parts of the process have been modified without considering all of the plant. Such actions will create imbalance in the process.

Understanding your process is key to cost-cutting success
At each stage of the process, there are both chemical and physical parameters that will impact the operation and productivity of the following stage and therefore affect the cost of production. The chemistry of the raw meal affects kiln operation and clinker quality; fuel properties influence the flame characteristics, again impacting on clinker quality and kiln operations; clinker quality affects the chemical and physical targets of the cement mill operation, and the quantity of materials such as limestone and pozzolan than can be used in the cement. In an intricate process, everything is interconnected. Knowing where cost reductions can be made really comes down to understanding your production process.

Sadly, due to staff cuts during mergers and acquisitions, and a lack of new talent entering the industry, many cement plants lack the skilled staff capable of this level of understanding. Fortunately, however, performance analysis can easily be outsourced with tools such as JAMCEM Consulting’s Performance Analysis and Diagnostics System and Virtual Technical Centre. If you’d be interested in learning where your efficiency is dropping out, get in touch.