The invention relates to a method for controlling the
fertilizer appearance by double-caramel
pigment. In the
fertilizer production process, the operation is carried out according to the following steps that (1) firstly, the double-caramel
pigment and the water are taken according to a
mass ratio being 1:0-0.5 and are mixed and stirred uniformly; (2) the double-caramel
pigment uniformly mixed in the first step is conveyed into a
slurry neutralizing tank by a
plunger type mechanical
metering pump, a
plunger type diaphragm
metering pump or a miniature single screw rod pump to be fully stirred with
fertilizer slurry, in addition, the double-caramel pigment is completely dissolved and mixed uniformly, one
ton of added double-caramel pigment fertilizer consumes 0.1 to 5.0 kg of double-caramel pigment, and a variable frequency flow meter is used for metering; and (3) the fertilizer
slurry mixed with the double-caramel pigment is pelletized, and the fertilizer in the required color is prepared. The method has the advantages that the fertilizer appearance can be conveniently regulated and controlled through the double-caramel pigment, the fertilizer color is uniform and stable, the
color mixing of fertilizers cannot occur, in addition, the consumption is low, the cost is low, the biodegradable effect is realized, the environment is favorably protected, the operation is convenient, no
pollution, no poison and no public
hazard exist, and the like.