‘Pump monitoring Promtex’ to improve their mining systems

The pigment industry faces challenges of maintaining product yield whilst also maintaining high standards in workplace safety. 

Many of the substances used in the pigment industry are subject to low workplace exposure limits (WEL) making reliable and repeatable control of the manufacturing process critical. 

Profitability of the business is also dependent on optimising process efficiency. 

The challenge: 

In most companies, occupational health monitoring takes the form of personal monitoring carried out every 6 or 12 months.  

Workers wear a personal device containing a pump connected to a filter to collect the dust matter they would be exposed to during a typical eight-hour shift. 

This is then taken to a lab to analyse the total dust exposure along with composition analysis and is generally performed to give indications of exposure to individual elements such as cadmium. 

This is a good way of ensuring that exposure doesn’t exceed current WEL’s; however, limitations arise because it cannot give information about the source of the exposure. This lack of information prevents the problem from being fixed in the future, which therefore doesn’t allow for process improvement. 

What solution does the Air XD Dust Monitor provide? 

Real-time dust monitoring allows for continuous monitoring of the production process. This enables the user to track typical emissions, whilst providing instant and accurate notifications if issues occur. 

The data generated can then be used to highlight parts of the normal production process that generate abnormal or problematic dust concentrations. It can also notify workers instantly if there is a process leak, or the extraction systems are not working correctly. 

In this scenario, the Air XD Dust Monitor provided the real-time data and area dust monitoring.  

How was the Air XD utilised? 

The Air XD Dust Monitor was used in a mobile configuration mounted on a tripod. This enabled the Air XD to be moved around the production plant to monitor the active process. The aim of the deployment was to monitor the levels of airborne dusts as well as monitoring for process leaks and variation. 

The Air XD Dust Monitor from Trolex uses optical particle counting (OPC) technology to dynamically count and size airborne respirable dusts in real time. This has many advantages over conventional monitoring techniques, which typically only give total exposure over a fixed monitoring period after that exposure has occurred. 

The key benefit for process monitoring is that because the data is time-stamped and has a very high temporal resolution (down to 10 seconds), it can be used to link raised levels of respirable dusts to a particular activity or process. 

The Air XD Dust Monitor was used by this customer to enable them to monitor the milling process, in turn helping them identify losses from the process that can be corrected, whilst reducing overall exposure for their workers. They have multiple vertical mills with increasingly fine respirable crystalline silica (RCS) dust produced at different levels of the mills.  

What was the Air XD used for? 

The examples given in this report highlight two areas where the customer was able to gather valuable data about their processes using the Air XD Dust Monitor. 

The first is an example of a process improvement/correction highlighted by the data provided by the Air XD and the second shows the benefits to occupational health monitoring of real-time data. 

The examples shown on the case study show particulate matter (PM) readings gathered alongside the silica milling process during a 24-hour period. Plots show data for PM10, PM4.25, PM2.5 and PM1. 

These refer to respirable dusts with diameters in different size bands. PM10 is equivalent to the dust that would be captured by a 10 µm filter in gravimetric sampling, PM4.25 a 4.25 µm filter and so on. 

Two examples were used. One showing the benefit of real-time dust monitoring data for the milling process, and another showing the benefits of real-time dust monitoring vs conventional post-exposure monitoring. 

Company overview: 

A specialist in developing, manufacturing, and marketing performance additives for the use in the construction, electronics, consumer products, agriculture, automotive, oil and gas industries worldwide. 

The main challenge: 

The drive to protect employees from potentially harmful respirable dusts is a priority for the company. They have identified prevention of exposure as the best form of protection, and, so, there is a drive to reduce the time their personnel spend inside the production facility. 

Whilst this ensures worker safety, it also generates its own problems; for instance, process leaks aren’t detected until an individual enters the production area and observes them. Due to the drive to limit exposure, this can lead to the loss of tons of product or raw materials before the problem is found. This loss of yield comes at a significant cost to the business. 

Multiple Air XD Dust Monitor devices were installed on site, with the aim of avoiding this on-going problem. 

How was the Air XD Dust Monitor utilised? 

Production at the site consisted of placing four vertical mills over two different buildings. In order to ensure that leaks were detected at different stages of the milling process, 14 Air XD devices were then installed in different positions around the plant. 

This also allowed the customer to easily identify the location any leaks that were detected. Air XD units were placed on different levels to monitor different parts of the process including the milling, drying and packing/loading areas. 

In order to meet the remote dust monitoring requirements of the customer, the signal and alarm outputs from the Air XD units were connected to a control panel located in the central control room. 

To maintain focus on dust generated by the production process rather than naturally occurring dust, the Air XD units were configured to focus on respirable dust in the PM4.25 range. In addition, since the majority of dust generated by the process were known to be silica dust, the particle density used in the airborne particulate density calculations was changed reflect this. 

This ensured more accurate dust monitoring of the true airborne particulate density and reduced the potential for false alarms. 

Company overview: 

One of the top three building/construction material manufacturers. 

Application: 

Mineral processing, crushing, and screening house. 

How long have they worked in the industry?  

Over 100 years 

What was the issue and how did Air XD Dust Monitor resolve it? 

• Forecasted ROI within six months 
• Notably reduced wastage of dust suppression materials 
• Safer environment for workers 
• Clear, specific, real-time reporting on PM (particulate matter) types and presence 
• No more reliance on ineffective monitoring methods 

Overview of the company processes: 

The amount of dust present in the air of the site’s enclosed buildings vary, as well as the composition of said dust. Due to the nature of the materials being processed, buildings within the site often have a high level of respirable crystalline silica (RCS) present. 

The levels of these dusts can fluctuate over any given period. The unpredictable nature of the site’s dust pattern made it very hard to effectively assess how safe their environment was to work in. In order to protect their work force, respirable protective equipment was used all the time and various dust suppression systems were implemented to try and control the amount of respirable dusts in the air. 

The way in which dusts were controlled was by using a visual inspection via CCTV from the main control room, this is a very common way of checking how the process is running and having a visual inspection of the dust levels being generated. 

The Air XD Dust Monitor experiment: 

After the client had given the detailed historical overview of their processes, a suitable location for the Air XD Dust Monitor experiment in the site’s process had been identified. 

We installed the Air XD Dust Monitor using the Transportable Pack, powering it via a 110 V supply. 

The purpose of this trial was to investigate how effective dust control tactics already in place on-site were for our client, and whether they made a difference to their dust levels that weren’t visible during visual inspections via CCTV. 

While visual inspections can identify whether there are any larger dust sizes present, this method of inspection can often miss the smaller and most dangerous PM sizes, all of which below PM10 are invisible to the naked human eye.