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Phosphates

Ingetecsa has built up a unique, in-depth experience in the Feed and Food phosphates with MCP, DCP, TCP and STPP.

We can offer the complete basic and detail engineering and also manufacture, supply and install the equipment for calcium phosphates.

Feed and Food Phosphates

Within the fertilizer and phosphate industries, calcium phosphates form an interesting niche market. They are the most widely used phosphate supplements, supply essential minerals for the development of strong teeth and bones in livestock, poultry, and pets.

Feed-grade calcium phosphates include:

Monocalcium phosphate (MCP)
Dicalcium phosphate (DCP)
Tricalcium phosphate (TCP)

Apart from as an animal feed supplement, calcium phosphates find their way also for instance in tooth paste, as texture enhancers, as sauce thickeners, as acidulates, as binders, etc. in food applications and the likes of industrial bakeries. Until now, only a minor fraction goes to pharmaceutical use.

Phosphate mine

BENEFICIATION PROCESS

Phosphate rock mining occurs all over the world. The largest reserves of high purity phos rock are in Morocco. The mined and crushed rock react together with sulphuric acid. Gypsum (phosphogypsum) and impurities then precipitate. Next is the acid de-fluorinisation, the de-arsenification and purification from heavy metals to obtain feed grade green or extra food grade white acid. The more rarely high purity white acid comes from elemental phosphorus rock in electric arc furnaces.

The acid and limestone react together to produce MCP, DCP and (rarely) TCP.

DCP production is also possible directly as a precipitate from attacking the phosphate rock with hydrochloric acid (substitution reaction). This niche process uses for instance waste hydrochloric acid from electrochemical plants / water dissociation. This DCP is mainly used for poultry feed, or further processed to feed grade MCP by adding phosphoric acid.

Process solutions

The tendency is to conceive a plant as flexibly as possible. For example to produce DCP powder, dust-free DCP/MCP micro-granules and MCP micro-granules indistinctly, allowing faster adaptation to market requirements.

In order to achieve a perfect quality of the calcium phosphate, four requirements must be met:

≡ The reagents must be well and energetically mixed
≡ Sufficient reaction surface and time has to be assured to finish the reaction and avoid free acid to remain in the mass
≡ In some cases (specially for MCP) dry product / dust is recirculated to ease the handling and produce in-specs granule sizes
≡ The equipment need to be powerful and duly oversized

The reaction and granulation can be divided into the following steps:

Ingetecsa reactor for DCP

Heavy duty, twin shaft reactor for the production of MCP or MCP/DCP micro-granules.

Pre-reaction: first mixing of reagents with a slightly sub–stoichiometric addition of acid
Reaction: additional acid brought in to fine tune the proportions
Maturation: The time for the reaction mass to solidify, harden, and to complete
Granulation/back-mixing: additional acid or water can be used to control the granulation when producing granular MCP or MCP/DCP micro-granules.

Ingetecsa Paddle mixers/reactors have proven to be the most successful technology for these applications.

Reactor configuration

Where the pre-reaction step can be done in a single shaft processor, the reaction step and granulation/back-mixing require twin shaft mixers with high shear mixing and self–cleaning capacities.

The reactor is designed to withstand the high forces that occur during the mixing and the hardening phase. Corrosion resistant materials are chosen to cope with the highly acidic products. Several acid intake points allow for process fine tuning. Spray nozzles help to reduce the generated dust. The design of the replaceable wear knifes and shaft seals make quick replacement during maintenance intervals possible.

The large amounts of CO₂ produced during the several stages in the process needs evacuation to the scrubber. The extracted gas contains significant dust loads and is sticky. A correctly designed hood minimises the risk of blockages during CO₂ extraction and in the ducting further downstream. Insulated or heat-traced hoods avoid condensation and build-up. Large hatches allowing entrance for scheduled inspection and cleaning intervals.

Flash drying

Until recently, the conventional Flash Dryer was the commonly used technology for these drying processes. Some manufacturers use rotary drum dryers. Flash dryers are reliable, and can deal well with the granular size and the product behavior.

Process flow diagram of the production of food and feed phosphates

Simplified process flow diagram of the production of food and feed phosphates

Newest drying technology

Recently, Ingetecsa started using the Spiral Flash Dryer as the next generation drying technology for this market segment.

The Spiral Flash Dryer has proven itself as a machine with a set of unique advantages over any other dryer:

≡ Totally static drying chamber
≡ Drying time of less than 10 seconds
≡ Proven higher thermal efficiency
≡ Less ortho-phosphates due to lower heating
≡ Less calcined DCP and MCP
≡ Very little maintenance, extremely reliable
≡ Capable of handling dusty DCP as well as granulated DCP or MCP without damaging granules

Principle of operation of the Spiral Flash Dryer

A unique dryer, ideal for food and feed phosphates.

Typical production site issues

The number of global production sites that manufacture MCP, DCP and TCP is low. New plants are typically designed based on theory only and on experience with other processes, supposedly of similar nature. Such new plants mostly have low availability rates until they are slowly improved by the operators based on trial and error.

The achieved improvements are mostly insufficiently documented, and rarely used elsewhere. There is little to no exchange of experience between the different producers. We see very different plant layouts for exactly the same process. As it is a small market, there are very few experienced specialists available for consultancy.

Maintenance

High maintenance and low availability due to a poorly designed process

Specialism when and where you need it

Ingetecsa is such a specialist. During many hands-on process improvements we have built up a great deal of in-depth knowledge in this field of phosphates.

The challenges in the processing of feed phosphates lie mainly in solid matter processing. Reactors, mixers, granulators, and the control of back-mixing have a major influence on the availability of the production process.

At Ingetecsa, we learned and demonstrated that good basic engineering and the specification of process conditions are crucial. The initial investment in correctly sized and designed heavy-duty equipment is quickly paid back, as the operational expenditures and unexpected down-times are significantly reduced.

Engineered the first time right

Engineered right the first time

Our promise

We pride ourselves on our track record of plants designed by us:

≡ Cleaning intervals stretched to (less than) once a week
≡ Availability tremendously improved
≡ Maintenance and spare part costs for ten years of operation rarely exceed 3 to 5% of the yearly machine costs only

That is good engineering!

If you’re interested in this technology, please get in touch. We’ll gladly invite you to discuss your project with one of our experienced process engineers.

Contact us for more information on MCP or DCP projects