US PATENT SUBCLASS 71 / 37
.~.~.~.~ Acid treatment

Current as of: June, 1999
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71 /   HD   CHEMISTRY: FERTILIZERS

1  DF  PROCESSES AND PRODUCTS {5}
31  DF  .~ Inorganic material {5}
32  DF  .~.~ Phosphorus-containing {1}
33  DF  .~.~.~ Phosphates {6}
37.~.~.~.~ Acid treatment {4}
38  DF  .~.~.~.~.~> Gaseous
39  DF  .~.~.~.~.~> Nitric and hydrochloric
40  DF  .~.~.~.~.~> Sulfuric acid
41  DF  .~.~.~.~.~> Acids of phosphorus

DEFINITION

Classification: 71/37

Methods of preparing phosphatic fertilizers where the starting materials are treated with an acid or a mixture of acids.

(1) Note. Methods employing mixtures of acids which are separately provided for hereunder are included in this subclass, e.g., a mixture of sulfuric and phosphoric acids.