No abstract

This article introduces a mechanochemical (MC) process for the synthesis of KMgPO4 and NH4MgPO4 by milling starting materials in a planetary ball mill. First, KMgPO4 was prepared by milling KHPO4 and Mg(OH)2 at a molar ratio of 1:1 for 120 min at mill rotational speeds of 500−600 rpm. Washing of KMgPO4 in water for 700 h released only up to 20−25% of K+ and PO4 2− ions into solution. Second, NH4MgPO4 was prepared by milling NH4HPO4 and Mg(OH)2 at a molar ratio of 1:1 for 120 min at mill rotational speeds of 300−700 rpm. Washing of NH4MgPO4 in water for 500 h released only up to 10−20% of NH4 + and PO4 2− ions into solution. The MC process could be developed to synthesize KMgPO4 and NH4MgPO4 for possible application as slow-release fertilizers.

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Synthesis of potassium/ammonium phosphates and alumina composites through a mechanochemical approach is presented for the first time. γ‐alumina and the phosphate are coground and the ground products are characterized by X‐ray diffraction and infrared spectroscopy. Quantitative evaluation of the remaining soluble part of the prepared amorphous phase at a low percentage around 10% demonstrates a potential use of the ground samples as slow‐release fertilizers.