Blog-News
Enhancing Efficiency of Ultra-Fine Air-Classification of Powders to Facilitate Global Reductions in Carbon Emissions from Food and Transport
Bradley Pulverizer Stainless Steel Classifier
Throughout Bradley Pulverizer’s history, we have collaborated with leading research institutions on particle milling and air classifying research initiatives and presentations.
Recently, the prestigious Wolfson Centre at the University of Greenwich partnered with us on a very exciting project involving the use of the Bradley Stainless Steel Windsifter Air Classifier. This project is significant for its focus on standalone air classification equipment, an often under-appreciated factor for meeting stringent specifications and increasing yields. This research provides scientific data to support important advancements in air classifier design. The study focuses on improving efficiencies of ultra-fine powder classification across protein shifting plant-based proteins to produce meat substitute. Improving the sharpness of cut of fine particle powders and high value materials can play a role in meeting stringent specifications and yield requirements across a variety of industries.
Zaki Hussaini, MEng, Design Engineer at Bradley Pulverizer, is a PhD candidate and researcher on this project.
The following is reproduced from the University of Greenwich, Wolfson Centre for Bulk Solids Handling Technology.
Origins of Superphosphate Manufacturing
Part 2 of a 5-part blog series: “The Bradley Broadfield superphosphate process”
The Broadfield process has remained a mainstay of the global phosphate industry since its introduction in the 1930s. Ian Hancock, Vice President Sales & Operations, Bradley Pulverizer, explains its continuing success in superphosphate production worldwide. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International Sept|Oct 2022, issue 510, pp. 31-35.
The early days of Acidulation
It is well known that crops require a supply of nitrogen, phosphorus and potassium for their sustenance – and that using fertilizers to correctly control the soil’s NPK balance is therefore essential for the long-term sustainability and commercial viability of agriculture.
While phosphorus is abundant in nature, the majority is locked away in insoluble form within crystalline phosphate rock. Indeed, phosphorus in its natural form offers little nutritional benefit to plants, as these can only absorb nutrients from the soil solution. That means there is a need to convert insoluble phosphate rock into plant-available soluble phosphates to support the productivity of global agriculture.
Introduction to the Bradley Broadfield Superphosphate Process
Part 1 of a 5-part blog series: “The Bradley Broadfield superphosphate process”
The Broadfield process has remained a mainstay of the global phosphate industry since its introduction in the 1930s. Ian Hancock, Vice President Sales & Operations, Bradley Pulverizer, explains its continuing success in superphosphate production worldwide. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International Sept|Oct 2022, issue 510, pp. 31-35.
The Bradley Broadfield process is the global standard for single super phosphate (SSP) manufacturing. Its flexible and reliable design is based on more than 100 years of SSP manufacturing experience and can produce SSP economically from all known phosphate rock sources.
The process is also used to make:
- Triple superphosphate (TSP)
- Monoammonium phosphate (MAP)
- Diammonium phosphate (DAP)
- Monocalcium phosphate (MCP)Dicalcium phosphate (DCP)
- Partially acidulated phosphate
- Synthetic gypsum
- Iron sulphate
- Other acidic salts
A Comparison of Mills Used for Phosphate Rock Grinding
There are similarities and differences between the mills that are most commonly used for commercial phosphate grinding. The following insight into the performance variables across the mill types helps to determine which mill is the right fit for specific phosphate grinding applications.
Bradley BM60 Pendulum Roller Mill
A brief introduction of 3 common mill types:
- Ball Mills – a horizontal rotating cylinder containing a charge of steel balls. The balls tumble as the mill turns and material caught between the balls is ground to powder.
- Table-Roller Mills – a horizontal table rotates with spring-loaded rollers mounted above. Material fed into the center of the table passes underneath the rollers and is ground to powder.
- Pendulum-Roller Mills – vertical rollers rotate inside a fixed horizontal ring. Material fed between the rollers and ring is ground to powder.
Similarities across the mills:
All 3 mill types require a continuous controlled feed, regulated to keep optimum conditions. This is done by selecting a suitable variable to control – noise is the standard method for ball mills; motor amps or pressure drop are used for roller mills. Also, all phosphate mills operate as air swept systems, using air to remove fine particles from the grinding zone to reduce the cushioning effect that they exert. This allows the grinding action to be concentrated on the large oversize particles, and is the key to efficient milling.
Case Study – Bradley Mill Overhaul and VBC Upgrade Results in Increased Up-Time, Higher Yields, and Lower Operating Costs
Market: Civil Construction/Limestone Quarry
Application: Grinding of limestone for use in tarmac for road manufacturing
The Challenge: LKAB Minerals needed to increase production rates and reduce maintenance downtime at the Hanson Aggregates Shap Quarry, where limestone is currently ground to 70-75% passing 63 microns for use in tarmac for road manufacturing. Outside of regularly scheduled maintenance, no major updates had been made to the existing Bradley airswept mill for over 13 years, and the mill has been continuously grinding coarse limestone materials for over 43 years.
Additionally, the existing mill system needed to process a wider variety of material grades to service a more diverse customer base. Finding a partner who could satisfy all requirements while following CDM guidelines was further complicated by the confined workspace around the mill, short installation time frame, and winter weather conditions.
Increased up-time of the Bradley mill would both improve efficiencies and lower annual production costs.
The Solution: The Bradley Pulverizer team was selected as turnkey manager responsible for all aspects of the project including all risk assessments, securing permits to work with exclusion zones, design and fabrication, installation, start-up, and training…..
Benefits of a Holistic Approach to the Mill System
Part 5 of a 5-part blog series: “The Importance of Phosphate Milling”
Bradley Pulverizer’s Ian Hancock, VP of Sales & Operations, discusses the importance of a holistic understanding of the phosphate milling process to ensure maximum plant uptime, the highest process efficiencies and profitability. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International July|August 2021, issue 503, pp. 49-52.
The upstream mill system may seem simple, compared to other systems in a fertilizer manufacturing plant. Nevertheless, it should still demand equal attention due to the invaluable role it plays in the overall quality, yield and profitability of the end product.
Any fertilizer product which contains Phosphate (P) as a key ingredient will be partly derived from phosphate rock. It should always be remembered, therefore, that it is the mill which is responsible for crushing this hard, friable material to the specified particle size and supplying the feed to all downstream processes. The mill system often remains the forgotten workhorse in fertilizer processing plants and, consequently, often lacks the credit it deserves in helping transform phosphate ore into fertilizer.
The Complete Fertilizer Milling System
Part 4 of a 5-part blog series: “The Importance of Phosphate Milling”
Bradley Pulverizer’s Ian Hancock, VP of Sales & Operations, discusses the importance of a holistic understanding of the phosphate milling process to ensure maximum plant uptime, the highest process efficiencies and profitability. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International July|August 2021, issue 503, pp. 49-52.
The key to optimizing mill system performance is the ability to effectively remove on-specification particles from the airstream and direct these as feed to the processing plant. In addition to the air-swept mill and classifier, the other components of the mill circuit include:
- Fans and ducts for the pneumatic transport of crushed particles
- A bag filter that cleans dust-laden air in a single-pass mill system or maintains suction within recycled mill systems
- An integrated heater to reduce moisture and improve production.
Critically, these ancillary equipment items complete the circuit and minimize energy usage as well as ensuring continuous output. Two main types of mill systems are available:
Classifiers: The Brains of the Operation
Part 3 of a 5-part blog series: “The Importance of Phosphate Milling”
Bradley Pulverizer’s Ian Hancock, VP of Sales & Operations, discusses the importance of a holistic understanding of the phosphate milling process to ensure maximum plant uptime, the highest process efficiencies and profitability. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International July|August 2021, issue 503, pp. 49-52.
Fine grinding with air-swept mills involves the continuous return of oversize material to the grinding zone for further reduction to the desired size. The role of the classifier is to control both the amount of recirculation inside the mill and the particle-size distribution of the product.
Essentially, the classifier functions as the ‘brain’ of the grinding circuit. Critically, it automatically determines:
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- What material should exit the mill as correctly sized product
- What should be returned for reprocessing.
Changing a classifier’s settings can significantly alter the milling system’s power consumption, capacity, vibration and product size distribution.
There are three main classifier types (Figure 1):
The Role of the Mill in Fertilizer Manufacturing
Part 2 of a 5-part blog series: “The Importance of Phosphate Milling”
Bradley Pulverizer’s Ian Hancock, VP of Sales & Operations, discusses the importance of a holistic understanding of the phosphate milling process to ensure maximum plant uptime, the highest process efficiencies and profitability. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International July|August 2021, issue 503, pp. 49-52.
Simply stated, the role of the mill in fertilizer processing is to crush/grind/pulverize the raw phosphate rock. Typically, the aim is to reduce quarter inch-size crushed rock into fine particles to meet the required specification for downstream processing or acidulation.
The degree of fineness and what particle size is acceptable varies significantly according to the production process and type of rock being used. This, in turn, influences mill selection. For an igneous phosphate rock, for example, single superphosphate (SSP) production requires a feed with 90 percent passing 53 microns. This falls to 90 percent passing 75 microns when sedimentary phosphate is consumed. When it comes to phosphoric acid production, 90 percent passing 150 microns is acceptable for the widely-used dihydrate (DH) process; whereas much coarser feed is acceptable for the hemihydrate (HH) process, with 90 percent needing to pass two millimeters instead.
Mill selection is primarily based on an ability to continuously crush hard, friable phosphate rock to specification. This needs to be carried out as efficiently as possible, given that this will dictate downstream yield rates and, ultimately, profits. The three main mill options for phosphate ore are:
The Essentials of Phosphate Milling for Fertilizer Manufacturing
Part 1 of a 5-part blog series: “The Importance of Phosphate Milling”
Bradley Pulverizer’s Ian Hancock, VP of Sales & Operations, discusses the importance of a holistic understanding of the phosphate milling process to ensure maximum plant uptime, the highest process efficiencies and profitability. Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International July|August 2021, issue 503, pp. 49-52.
Grinding and pulverizing mills are the furthest upstream process in phosphate fertilizer manufacturing. The continuous crushing of phosphate rock to meet particle size specifications is essential for efficient downstream processing. Yet mills are more commonly seen as the ‘noisy neighbor’ to other process steps, rather than the essential engine that drives phosphates production. Regrettably, this lack of recognition for the importance of milling can cause inefficiencies upstream that are further compounded downstream.
Phosphate rock is fed into the front-end of a production plant and manipulated many times during its long process journey and eventual transformation into valuable end-products. This continual production process is central to efficient phosphate fertilizer manufacturing, with each process stage requiring specialized equipment.
