Importance of Bubble Size Distribution in Modeling in Gas-Liquid Stirred Vessels
Importance of Bubble Size Distribution in Modeling in Gas-Liquid Stirred Vessels
Ravindra Aglave - Siemens/CD-Adapco

Gas-liquid systems form a key component many chemical industry processes. In such systems, the knowledge of gas volume fraction, its distribution and its eventual effect on mass transfer and reactions is absolutely essential. Experimental measurements have allowed to look in to such systems to a good level of details, resulting in to generation of correlations. These correlations are commonly used in the design process. However, they are very much limited to the size, type and character of the lab or pilot scale system from which they were created. This leaves process engineers with a task of ascertaining if a particular design will meet all the process conditions or not. CFD simulations have allowed process engineers to look at plant scale designs due to the ability to investigate them virtually using computer models.
In many such models, certain assumptions are made. As more research and numerical techniques are developed, these assumptions are relaxed to gain more accuracy. In gas liquid flows, it is commonly assumed that the bubble sizes are uniform or have a mean value. However in reality, there is a varying size of bubbles. This assumption can introduce large error in the calculation of gas volume fraction. Moreover, it can give a misrepresentation of the distribution as well. This means there could be area where the gas volume fraction could be critically lower than process requirement, destabilizing the process or even an unsafe condition. In this paper we present the results from a simpler method, known as S-gamma model, which accounts for coalescence and break up of bubbles and uses only a distribution function.
Last updated: 2017-04-17

The Importance of Phosphate Process Optimization from Mine to Market
The Importance of Phosphate Process Optimization from Mine to Market
Todd Parker - ArrMaz

Phosphate is a non-renewable resource and must be managed accordingly. Understanding the phosphate industry from beginning to end is the key to unlocking the true potential of phosphate ore to produce superior quality fertilizer sustainably and cost-effectively. Describing 10 key practices for better rock processing to improve grade and recovery thereby creating a more valuable rock and better feed stock for fertilizer plants, enabling them to produce higher value fertilizer. Better quality fertilizer in turn delivers greater benefits to farmers, improving crop yields, livestock nutrition and food quality to meet the needs of a growing global population. Mining chemicals and fertilizer process aids are essential to creating such value throughout the phosphate fertilizer supply chain.
Last updated: 2017-04-16

Quality Parameters in Crystallization
Quality Parameters in Crystallization
Sven Hanselmann - Ekato

Crystallization is a wide spread process step in many applications like food, chemicals, APIs or fertilizers. There are three main routes to form solids by crystallization

1. cooling
2. evaporation
3. precipitation

Depending on the applicable route, the mode of operation is either batch wise or continuous.

This paper will focus on the relevant quality parameters in crystallization. It is demonstrating by examples how to control formation of solids by optimized process conditions, i.e. cooling/evaporation strategy, seeding of crystals and vessel design as well as the influence of agitation.

In an optimized system the particle size distribution can be narrowed and the impact on the crystals, e.g. breakage or the production of fines will be reduced. This offers additional benefits in downstream process steps like filtration, drying or packing. The filters’ design can be simplified and the flow behaviour will be improved.

Examples like improved flow patterns in a draft tube baffled crystallizer or shear reduced mixing systems will be described and are supported by lab test results and computational fluid dynamic (CFD) simulations.


Last updated: 2017-04-16

Mosaic New Wales MicroEssentials Conversion
Mosaic New Wales MicroEssentials Conversion
Doug Belle - Hatch, TBD - Mosaic

Mosaic is the world’s leading producer and marketer of concentrated phosphate and potash fertilizer products. In 2013, Mosaic identified a project that would provide the additional production capacity needed to meet increased market demand for Mosaic’s patented MicroEssentials (MES) Products. Mosaic selected Hatch to provide full Engineering, Procurement and Construction Management (EPCm) services for the New Wales MicroEssentials Project. The project included the conversion of an existing dual train (East and West) Di-Ammonium Phosphate (DAP) Plant to MES and Granular Mono-Ammonium Phosphate (MAP) Production. The scope of work for this project included the installation of new closed circuit scrubbing systems, modifications to the recycle system to increase capacity, new ammonia vaporizers, new 65,000 ton product warehouse with automatic re-claimer, new sulfur pit with molten sulfur transfer systems and the facilities for the unloading, storage and pneumatic conveying of micro-nutrient raw materials for the production of MES products. The Hatch Tampa, Florida Office worked together with Mosaic and executed Front End Loading (FEL) 2-Pre-Feasibility, 3-Feasibility, 4-Detailed Engineering and provided Procurement, Construction Management and Commissioning Services for this multi-million USD Capital Project. This paper will present the overall scope of work for the project and discuss the challenges related to the engineering and construction of a heavy brown-field granulation plant project.
Last updated: 2017-04-16

CFD Simulation to Improve Cooling Pond Performance
CFD Simulation to Improve Cooling Pond Performance
Andrew Nuyianes, Angelo Stamatiou, Debbie Stetka, Jianping Zhang
Hatch Ltd

Cooling ponds are used in the phosphate and mining industries to provide relatively adaptable and low energy cost solutions. The performance of these ponds may be affected due to improper design and control. To optimize pond design and management, a comprehensive three-dimensional computational fluid dynamic (CFD) model has been developed. The model accounts for all the heat transfer mechanisms including solar radiation, evaporation, conduction and convection.

A full-scale case study is presented for a cooling pond in a phosphate fertilizer facility. A base CFD model was developed to investigate the flow field and temperature profiles in the pond under selected operating conditions. The results suggest that once the base case model has been developed, the CFD pond model can be very powerful in troubleshooting the operating issues of the existing pond and quantifying the key factors affecting the pond heat transfer.
Last updated: 2017-04-16

Maximizing P2O5 Effects from Di-Hydrate
Maximizing P2O5 Effects from Di-Hydrate
James Byrd, Elton Curran - Jacobs

Phosphoric Acid plants are benchmarked by production and yield, typically in terms of P2O5. Production has been the benchmark, but as the industry evolves and economics tighten the importance of yield is becoming more pronounced. Yield, also referenced in terms of recovery or losses, is a complex evaluation when studied in detail. Often, yield across the filter, typically quoted by licensors, is confused with yield across the plant. The latter is more appropriately termed Global Recovery and can be complex both in measurement and in control. Global Recovery is simply the difference between P2O5 fed to a reactor and P2O5 produced in terms of phosphoric acid. The losses across the filter are relatively easy to measure, but accounts for only a fraction of Global Recovery. The differential can be substantial and in some cases can be larger than filter losses. This differential is often termed mechanical losses and can result from shut downs, wash downs, equipment malfunctions and other miscellaneous operational factors. There are proven methods to mitigate mechanical losses in the plant as well as losses across the filter. This paper will discuss such methodologies for both existing and conceptual facilities.
Last updated: 2017-04-16

Feasibility of Solar Panels
Feasibility of Solar Panels
Jennifer S. Woodson - Mississippi State University

Solar energy is a cleaner, but more expensive option than producing energy using fossil fuels. However, research and development of solar energy efficiency is rapidly evolving. Although requiring an initial high capital cost; the payback may only be a few years (dependent upon the location of installation). Solar cells manufactured today are expected to last at least 25 years. Solar cells now have the ability to be quite profitable as well as positively impact the environment.

This paper will evaluate both the financial and environmental impact of solar cell use. Financially there are U.S. federal tax credits, renewable energy credits and carbon credits that can improve solar energy profitability. Environmentally, there are both benefits and drawbacks to each option. What is the best use for cleared land? This paper investigates various agricultural options, timber options, and solar panels options for cleared land in the south-eastern United States.

In 2016 the Paris Agreement was signed and ratified by the United States. The Paris Agreement is a United Nations Framework Convention on Climate Change (UNFCCC) agreement with the goal of maintaining the increase in global temperature to less than 2°C (in the past 100 years the Intergovernmental Panel on Climate Change has reported the global temperature increase by 0.85°C. There is much scientific dispute on what is responsible for the increase in temperature. Perhaps it is natural? Perhaps it is the cause of carbon emissions? Regardless of the cause, The Paris Agreement is going to force business’ producing carbon emissions to scale back on their carbon emissions. One of the largest sectors with high carbon emissions are coal-fired power plants. However, this is currently the cheapest producer of electricity. If power companies are required to meet tighter carbon emission standards, the cost of electricity will significantly increase.
Last updated: 2017-04-16

Increasing Recovery in Reverse Flotation
Increasing Recovery in Reverse Flotation
Kevin O’Brien, Jianjun Liu, Paul Wiatr, Nalco Water

The effects of a new reagent for the phosphate industry reverse flotation process were examined in the laboratory. Reagents including collectors and depressants have been widely studied for the flotation of gangue from phosphate containing minerals (apatite). Nalco Water has studied the performance of a new reagent which helps to depress the apatite and improve the efficacy of flotation separation. Laboratory test work was conducted in accord with statistical design of experiments to study the effects of phosphoric acid depressant and the new reagent on concentrate grade and recovery from reverse flotation. Experimental results indicate that the addition of this new reagent can increase phosphate recovery by as much as 3% with no decline in concentrate grade. Additionally, application of this new reagent decreases the need for phosphoric acid, used as a depressant, by as much as 50%.

The relationships between the flotation reagents and how changes in dose ratio affect recovery and grade are detailed herein. These relationships were then used to create several business scenarios that highlight the potential benefits to the phosphate industry. This Nalco Water reagent provides a new tool which can be used to maximize recovery and increase profitability.

Last updated: 2017-04-16

Application Benefits of Safety Integrity Level Gas Detection Instruments
Application Benefits of Safety Integrity Level Gas Detection Instruments
Steve Phelps - Sensidyne

Phosphate chemical processing has always been considered as having the potential for a hazardous release of toxic gases which could cause personnel injury or loss of production and even off-site consequences. To reduce this risk, certified Safety Integrity Level gas detection instruments are being applied to identify hazardous gas leaks quickly and correctly. The timely warning of a potentially hazardous condition to process and personnel provides time for mitigation, unit evacuation or shutdown before a catastrophic event can occur.

This paper examines the application benefits of SIL certification to IEC 61508 for enhanced reliability, risk reduction and safety instrumented systems. A discussion of gas sensor predictive failure, gas sensor performance certification and the unique Intrinsic Safety approval of the gas sensor interface is also provided. Toxic endpoints are defined and an example for Ammonia is given with regard to off-site consequences.
Last updated: 2017-04-16

Umm Wa'al Phosphate Project - Sulfuric Plants
Umm Wa'al Phosphate Project - Sulfuric Plants
Daniel Freeman - SNC Lavalin

SNCL’s portion of the project consisted of:
3 x sulfur burning Sulphuric Acid Plants each producing 5050 MTPD ( of 100% H2SO4) at 98.5% H2SO4 and 261 tph steam at 65 barg and 500 °C
1 x Auxiliary Boiler producing 270 tph steam at 63.5 barg and 495 °C
2 x Steam Turbo-Generators each producing 74 MW of electricity, mainly for export.


The project presented several challenges:
Timeframe –very tight, from engineering, through to commissioning.
Location –arid, dry climate –limited water available. Recycle/reuse necessary.
Size –the sheer size of the plant challenged our engineering group to come up with some novel solutions. The dry gas equipment, and the Converter especially required some new thinking. The large free-span areas and gas distribution presented problems to be solved.
Commissioning -the 3 SAPs and an Auxiliary Boiler are all able to provide steam to the STGs, and also to the LP steam users elsewhere at PAP and sulphur heating etc. The complexity of the steam pipe layout made the commissioning a challenge.

Last updated: 2017-04-16

Phosphorus Removal & Recovery from Enhanced Biological Phosporus Removal Sludge
Phosphorus Removal & Recovery from Enhanced Biological Phosporus Removal Sludge
Nadezhda Zalivina, Maraida Balaguer-Barbosa, Andres Garcia Parra, Sarina Ergas - University of South Florida, Luke Mulford, Public Utilities Department, Hillsborough County.

Excess phosphorus in surface waters causes algal blooms and consequent eutrophication. One of the sources of phosphorus is wastewater effluent. Therefore, prior to discharge, phosphorus should be removed from the wastewater. At the same time, phosphorus is a limited resource and phosphate mining is a
very energy intensive process, which has negative impacts on the environment.

Enhanced Biological Phosphorus Removal (EBPR) is a popular wastewater treatment process worldwide. During EBPR phosphorus is taken up by polyphosphate accumulating microorganisms, stored inside their cells and subsequently removed from the wastewater with the waste activated sludge. The anaerobic digestion of the sludge is used for bioenergy recovery in the form of methane, which makes the wastewater treatment process more energy efficient. However, during the digestion of EBPR sludge, stored polyphosphates are released and carried in a sidestream. Sidestreams are typically recycled back to the head of a treatment plant, thus, making the treatment process highly inefficient (increased treatment costs). One successful option for phosphorus removal and recovery is struvite precipitation. Struvite (MgNH4PO4) is a mineral that can be used as a substitute for phosphate fertilizer, thus, generating a possible revenue for wastewater treatment plants. In addition, struvite is a slow release fertilizer, which application reduces non-point sources of pollution. Currently, there is a lack of information about struvite precipitation from sidestreams produced during the digestion of EBPR sludge.

A thermophilic anaerobic digester with the working volume of 24 liters (L) and hydraulic residence time of 12 days was operated in the lab at the working temperature of 55±2°C. The digester was fed three times a week with EBPR sludge from the Falkenburg Advanced Wastewater Treatment Plant (Brandon, Florida). The sidestream containing high concentrations of phosphorus as well as nitrogen was used as an influent for the 4-L fluidized bed reactor used for struvite precipitation. Prior to as well as after the precipitation, the sidestream was centrifuged to remove the solids. The sidestream was seeded with some commercially produced struvite seed from Ostara® and its pH was raised to 8.5 by 2N NaOH addition. If necessary, magnesium salt was also added based on the stoichiometric ratio Mg:NH4:PO4 (1.3:1:1).

The preliminary results showed a substantial phosphorus removal (95-99%) as well as a significant removal of nitrogen (25%) from the sidestream. This indicates that struvite precipitation can help reduce the impact of phosphorus on the environment as well as generate a revenue stream for the wastewater treatment plants which can offset some of the operating costs. A side benefit of
phosphorus recovery is nitrogen recovery. Struvite precipitation can decrease the concentration of nitrogen recycled back with the sidestream, which reduces energy and chemical requirements.

Last updated: 2017-04-17

Fuming Acids Spill Mitigation Training
Fuming Acids Spill Mitigation Training
Mark Salzbrenner, & Brad Van Scoik - VEOLIA NORTH AMERICA

Fuming sulfur-based acids (sulfur trioxide, oleums and chlorosulfonic acid) are essential chemicals to today’s society. If handled properly, they are relatively easy chemicals to transport and store. If not, and are they are released to the environment, they can create very visible (and hazardous) fumes (dense white acid mist clouds) at low concentrations.

As part of Veolia NA’s Product Stewardship program for the Fuming Acids, we offered training on Fuming Acids Spill Mitigation at the DOE's HazMat Spill Center in Mercury, Nevada in May 2016. Customers, transporters, mutual aid responders and local community HazMat teams were invited to participate in one-week long training sessions. In these “hands-on” sessions the participants responded to “live” spills of the Fuming Acids and taught how to mitigate the ensuing “white cloud”. The hands-on participants donned Level A full-acid training suits with breathing air and mitigated the spill with either water spray, foam or dry-chemicals. The objectives of the training were:
• Train in mitigation technology and visually compare the mitigation techniques
• Witness fume clouds which result from the release of the fuming acids
• Reinforce the importance of keeping the acids properly contained
• Enhance emergency preparedness
• Test new mitigation techniques and/or equipment.

In addition we tested a number of “new” foams for their efficacy on fume mitigation. The foam manufacturers are required to eliminate the “traditional” C-8 foams by the end of 2016 and replace them with C-6 foams for environmental concerns.

Last updated: 2017-04-17

Reduction of Phosphogypsum by Optimizing Final Product Mix
Reduction of Phosphogypsum by Optimizing Final Product Mix
Curtis Griffin - PegasusTSI

The production of wet phosphoric acid generates 5 tons of phosphogypsum per ton P2O5. Phosphogypsum refers to the gypsum formed as a by-product of the production of fertilizer from phosphate rock. Phosphogypsum is mainly composed of gypsum (CaSO4·2H2O). Although gypsum is a widely used material in the construction industry, phosphogypsum is usually not used, but is stored indefinitely because of its weak radioactivity. The US EPA has banned all applications of phosphogypsum due to the low radiation levels. The storage and handling of phosphogypsum is very expensive and eventually additional land is required for new stacking.
The ability to reduce the amount of phosphogypsum produced per ton of P2O5 can result in reduced costs and extended stack life. This paper will show how final product mix can reduce the amount of phosphogypsum produced. Products such as Single Super Phosphate (SSP), Dicalcium Phosphate and Monocalcium Phosphate from Hydrochloric Acid (HCL), Granulated Triple Superphosphate (GTSP), lower grade Monoammonium Phosphate (MAP) and addition products can reduce the amount of gypsum produced or in some cases eliminate phosphogypsum production all together.
The various products mentioned above and others will be discussed, basic flow sheets will be reviewed and the reduction in phosphogypsum per ton of P2O5 will be shown. The impact on costs and stack life will also be evaluated.
Last updated: 2017-04-17

What To Do When You Run Out of Blower
What To Do When You Run Out of Blower
John Horne - MECS / DuPont

When constructing a new acid plant, overall plant rate can be adjusted by examining different blower sizing. After the plant is built, blower characteristics are no longer a variable; they are a constraint. As plants inevitably aspire to achieve higher and higher production rates, it is common for the blower to become the limiting factor. Seemingly at this point, the plant has “run out of blower.”

This paper will examine precisely this situation. What options do plant owners and operators have when they need more capacity, but must face the reality associated with limited blower capacity? Specifically, this paper deconstructs the acid plant from front to back and examines options for releasing additional capacity by reducing gas side pressure drop without changing out the blower. Real cases are studied and hard data is presented to show the relative costs, benefits, and other impacts associated with various solutions to the classic challenge of increasing production targets with a fixed blower design.
Last updated: 2017-04-17

Phosacid Storage Tanks: Why do they build up with solids?
Phosacid Storage Tanks: Why do they build up with solids?
Todd Hutchinson - Philadelphia Mixing Solutions Ltd.,

Phosacid Storage tank agitators are typically sized for off-bottom solids suspension. Customers have reported that this design requires the tanks to be cleaned out every 6-12 months. Cleaning can involve days to remove the solids and often results in damaged tank linings requiring repairs.

We have found sizing for solids suspension is not the only requirement that needs to be taken into account. There are heat transfer effects that, if not addressed, allow for gypsum formation on the walls. Over time the large formations break off and fall to the floor. In some cases the build-up was enough to damage the agitator.

This presentation will discuss how to solve for this wall build-up allowing for much longer time between inspections.

Last updated: 2017-04-17

Use of Composite Nonmetallic Materials in Sulfuric & Phos Acid Facilities
Use of Composite Nonmetallic Materials in Sulfuric & Phos Acid Facilities
Michael Yee , Richard Taraborelli - RTConsultants

Most sulfuric and phosphoric acid plants utilize extensive nonmetallic solution in processing units. In order to address these harsh chemical environments, specific corrosion engineering and materials needs must be specified and applied correctly to prevent operational issues.
Conventional FRP (Fiber reinforced plastics), rubber linings, and acid brick towers are commonly used with success in these environments. This paper will discuss the use of composite nonmetallic materials commonly used in sulfuric and phosphoric acid facilities. In addition, the paper will go into case studies and lessons learned from successful projects covering the importance of inspection and quality assurance for reliable service life.

Last updated: 2017-04-17