New solutions for producing high-purity MAP fertilizer

GEA is helping manufacturers to meet some of these challenges and reducing their production costs in the process.

The world’s population continues to grow, and with it comes the most basic requirement: the need to adequately feed more people, including those in regions where soil nutrients and rainfall are less than ideal for raising crops. Ecologically, the challenge is to produce more food, including fruits, cereals and vegetables, without increasing our environmental footprint.

Fertilizer will play an important role in reaching this goal. However, the industry and growers need to find the right balance of inputs, minimise losses to the environment, reduce nitrate levels in groundwater, emissions of greenhouse gases, soil pollution, as well as surface runoff of nitrogen and phosphorous nutrients, which hamper oxygen production in water bodies.

Increasing demand for water-soluble fertilizers

Multi-nutrient (NPK) fertilizer still dominates the landscape, however growers are increasingly looking for high-purity and water-soluble formulations for foliar applications where the same is applied directly to a plant’s leaves or foliage. If an irrigation system is used, this is referred to as fertigation, a new term constructed from the words ‘fertilization’ and ‘irrigation.’

The precise number of nutrients made available to the plant is easily controlled and they are taken up quickly, reducing the chances that fertilizer is wasted or toxifies the soil due to over-fertilization. Given their low salt content, water-soluble fertilizers are less likely to burn plant tissue or clog spray systems and pumps.

Several types of water-soluble fertilizers are available today, including monoammonium phosphate or MAP, which is a widely used source of phosphorus and nitrogen and contains the most phosphorus of any common solid fertilizer. MAP is widely used at the beginning of the growth season when phosphorus availability is crucial for the establishment of the root system, but it can also be tank-mixed with other fertilizers to meet crop nutritional needs throughout the growth cycle. Produced as a white crystalline pellet, it is highly concentrated and characterised by the following key attributes:

• Fully water-soluble.
• Free of chlorine, sodium and other elements like heavy metals – all of which are harmful to plants.
• Moderate pH value (safer and less corrosive); especially desirable for neutral and high-pH soils.
• Suitable for fertigation and foliar applications and production of fertilizer blends and nutrient solutions.

Raising the bar and lowering the cost of MAP fertilizer production

In the production of MAP, high-purity phosphoric acid is generally used as the starting product. GEA has developed and implemented a ground-breaking solution to produce high quality soluble MAP fertilizer that eliminates:

• The need to purchase purified phosphoric acid.
• The need to integrate an additional purification line.

The solution is already being successfully used by a GEA customer in Eastern Europe who was able to avoid considerable capital and operating expenditures thanks to the use of non-purified, merchant grade phosphoric acid, yet still achieve a high-purity MAP fertilizer, which as a product has a high market value.

“We began with very small-scale lab tests to better understand the product behavior, then proceeded with tests on larger samples. Next, we tested the entire process with pilot plants for separation, membrane filtration, evaporation and crystallisation technology,” explains Giedrius Gudeika, head of solutions sales, GEA Baltics.

After just six months of trial and error, the GEA team finalised a solution that allows the customer to use up to 30% of its non-purified phosphoric acid feed to produce pure soluble MAP fertilizer while the remaining 70% is used to make standard granular MAP fertilizer.

Read the article online at: https://www.worldfertilizer.com/nitrogen/16042019/new-solutions-for-producing-high-purity-map-fertilizer/