Possibility of using chalk in production of mineral-organic fertilizers

anglais. Chalk, due to its physical properties and high reactivity, seems to be an interesting component for production of various types of fertilizers. This mineral can be mixed with other components both organic and minerals. Among the potential additives, we can indicate digestate, all kinds of biomass, elemental sulfur, phosphates, and nitrogen in the form of urea. The formulation of such fertilizers requires a series of investigations related to the physical and chemical effects on plants and soil environment. It is also important to select the best formulation method for specific mixtures. The paper presents comprehensive research on chalk based fertilizing mixtures. As additives several substances were chosen: digestate, biomass, sulfur, phospates, and urea. The formulation process was analysed form milling of the materials to fine powder, mixing to homogenise components, and agglomeration. The formulation of the granules was according to two most commonly used methods - pressure formulation on flat die granulator and the non-pressure method (disc granulator) most commonly used in fertilizer industry. In addition, chemical analysis of the proposed mixtures was performed to assign quality of the proposed blends. The presented results have shown that granulation of chalk both in combination with minerals and with organic materials is possible. Chalk with low water content can be very well mixed with all investigated materials. What is also important, dry material can be added to more wet (organic) substances and can be a very good material for balancing moisture in the final fertilizer mixture. It is also favorable, because drying of chalk is more effective than organic materials, where water molecules are more strongly associated. This would lead to lower energy consumption during production of the fertilizers. The tests carried out show clearly that chalk is a good ingredient in fertilizer production based on pressure and nonpressure agglomeration.

anglais. lake chalk, compaction, agglomeration pressure, fertilizers

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