Slow-release fertilizer from a rock containing glauconite by thermal processing with additives

• DOI: 10.22533/at.ed.01719091017

• Palavras-chave: ATENA

• Keywords: potassium; slow release fertilizer; thermal processing; glauconite.

• Abstract:

  Glauconite is a monoclinic mineral,

  of green color, a potassium and iron hydrated

  phyllosilicate. It is an alternative source of

  potassium, but still not being commercially

  exploited in a large scale for this purpose, due

  to the lack commercial technology that makes

  the business economically viable. This work

  investigated the dissolution of potassium in a

  solution of citric acid 2% (m/m) after thermal and

  chemical processing, with additives (CaCO3,

  MgCl2.6H2O), of a rock containing glauconite at

  six temperatures: 660°C, 700°C, 740°C, 780°C,

  820°C and 860°C, 60 minutes and granulometry

  smaller than 0.15mm. The mass ratio (rock,

  CaCO3, MgCl2.6H2O) was: (1.0: 0.2: 0.3). A

  rock containing glauconite with a content of

  11.9% K2O and 58% glauconite was selected.

  The potassium extraction was evaluated by

  extraction in 2% citric acid solution (m/m) at

  95°C for 15 minutes and in water at 90°C. The

  solubility in water was 21% (770°C) and in

  citric acid the highest potassium extraction was

  78% at the temperature of 770°C. The curve

  passes over a maximum (770°C), showing that

  there is a limit to the temperature in the thermal

  processing. Above this value, there is a drop in

  the extraction indicating different mechanism

  of reaction between the rock and additives.

  By considering that in water, the solubility of

  potassium was 4 times lower than in citric acid,

  it can be concluded that the thermal processing

  makes Verdete ore a potential alternative source of potassium for the production of

  slow release fertilizer.

• Número de páginas: 15