FORM 2
THE PATENTS ACT 1970 (39 OF 1970)
& THE PATENTS RULES 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION PROCESS FOR MAKING DUST FREE ZINC PHOSPHIDE FORMULATION
APPLICANT
AIMCO PESTICIDES LIMITED
An Indian Company
Akhand Jyoti, 8th Road, Santacruz East
Mumbai 400055, Maharastra, India
The following specification particularly describes the invention and the manner in which it is to be performed

PROCESS FOR MAKING DUST FREE ZINC PHOSPHIDE FORMULATION
FIELD OF INVENTION
The process invention relates to an improved process for preparing dust free zinc phosphide formulation for ease of handling and personal safety during manufacture and field application.
The zinc phosphide powder is coated with edible vegetable oil by spraying in a suitable mixing equipment under dry atmosphere (moisture free ) to prevent the degradation of zinc phosphide powder and release of toxic phosphine gas.
BACKGROUND OF INVENTION
Zinc phosphide dust free is used for conversion in to rodent control bait by mixing it with grain (wheat, rice) crops. The edible oil coating makes the zinc phosphide dust free ( product) safer for handling by workers. The zinc phosphide powder due to its hygroscopic nature absorbs the moisture from the air and releases very dangerous / harmful gas namely phosphine gas which is very much toxic/fatal to the workers during handling and field application. Therefore it is the need for the workers to handle this toxic Zinc phosphide with proper management through a process of coating the said material in such a manner so that the harmful effect of the Zinc phosphide can be reduced.
STATEMENT OF INVENTION
The process invention relates to a process of coating zinc phosphide powder in an efficient blender with edible vegetable oil (0.5 - 5.5 percent by

wt of zinc phosphide powder) at a temperature between 20 - 60° C in a dry
moisture free atmosphere.
The novel process for making zinc phosphide dust free formulation of
coating the zinc phosphide powder with edible vegetable oil there by
making the product more safe for handling, transfer and field application by
human people.
The different edible vegetable oils used for zinc phosphide dust free
formulation are as under. And they act as an attractant to rodents.
a. Coconut oil (CAS NO: 8001-31-8),
b. Corn oil (CAS NO; 8001-30-7),
c. Cotton seed oil ( CAS NO. 8001-29-4),
d. Olive oil ( CAS NO. 8001-25-0),
e. Palm oil (CAS NO. 8002-75-3),
f. Peanut oil (CAS NO. 8002-03-7),
g. Rapeseed oil ( CAS NO. 8002-13-9),
h. safflower oil ( CAS NO. 8001-23-8),
i. Sesame oil (CAS NO. 8008-74-0),
j. Soybean oil (CAS NO. 8001-22-7), k. Sunflower oil (CAS NO. 8001-21-6).
From all above vegetable oils, sunflower oil, Olive oil, and Soybean oil are
chiefly used for coating of the zinc phosphide powder and safe dust free
formulation.
The mixing equipment employed is double cone slow rpm blender in steel
construction with inflight baffels for uniform blending and coating of edible
vegetable oil and the blender equipment is housed in a dehumidified room
with packing arrangement.
DESCRIPTION WITH EMBODIMENTS
The invention relates to a process of coating zinc phosphide powder with edible vegetable oil selected from the group consisting of olive oil, soybean oil and sunflower oil.

In carrying out the present invention, the mixer room is dehumidified by
suitable means to a dew point at or around plus 5° C to minus 10° C. and
maintained.
The double cone blender is charged with zinc phosphide powder 94.5 -
99.5 kgs and blender started. The rotational speed is adjusted between 5 -
20 rpm. Followed by addition of 0.5 - 5.5 kgs of edible vegetable oil. (The
edible vegetable oil is introduced as a spray inside the blender in three
lots of spray to coat the zinc phosphide powder at regular interval ) to
make the standard batch of 100 kgs dust free formulation. The blender
inside temperature is maintained between 20 -60° C and the zinc phosphide
dust free coating takes around 2 - 6 hours.
The blender is then stopped as the zinc phosphide dust free formulation is
ready. The product is then discharged from the blender and packed into
suitable container in the same dehumidified room.
The following example illustrates the invention:
EXAMPLE 1
The blender room is first dehumidified for 30 minutes at a dew point of plus 5 -6CC and maintained.
The double cone blender is charged with zinc phosphide powder 97.0 kgs The rotation is started and speed of rotation is adjusted to 8 rpm. Followed by addition of edible sunflower oil 1.65 kgs by spraying inside the rotating blender and coating of zinc phosphide powder is continued for 1.0 hour. The temperature during the coating is maintained at around 30 -31° C. Another lot of 1.25 kgs of edible sunflower oil is further sprayed inside the blender during rotation and the coating of zinc phosphide powder is continued for further 1.5 hours. The remaining third lot of 0.10 kg of edible sunflower oil is finally sprayed inside the blender while the rotation is on. The final coating of zinc phosphide powder is continued for another 2.0 hours.
The blender rotation is then stopped. The total time for completion of zinc phosphide dust free formulation is 4.5 hours.

The formulated zinc phosphide dust free is obtained i.e. 100 kgs and packed in suitable container in a dehumidified area of blender room.
EXAMPLE 2
The blender room is first dehumidified for 30 minutes at a dew point of minus 9 -10° C and maintained.
The double cone blender is charged with zinc phosphide powder 97.9 kgs. The rotation is started and speed of rotation is adjusted to 15 rpm. Followed by addition of edible soybean oil 1.10 kgs by spraying inside the rotating blender and coating of zinc phosphide powder is continued for 45 minutes. The temperature during the coating is maintained at around 35 -36° C. Another lot of 0.85 kgs of edible soybean oil is further sprayed inside the blender during rotation and the coating of zinc phosphide powder is continued for further 1 hour 15 minutes. The remaining third lot of 0.15 kgs of edible soybean oil is finally sprayed inside the blender while the rotation is on. The final coating of zinc phosphide powder is continued for another 1.0 hours.
The blender rotation is then stopped. The total time for completion of zinc phosphide dust free formulation is 3.0 hours.
The formulated zinc phosphide dust free is obtained i.e. 100 kgs and packed in suitable container in a dehumidified area of blender room.
The present invention has been described with reference to the preferred embodiment purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the scope of what has been described herein before and claimed in the appended claims.

WE CLAIM
1 A process of making a formulated dust free zinc phosphide in an
efficient blender through coating of zinc phosphide powder with edible
vegetable oil by spraying and blending the edible vegetable oil in three lots
intermittently at fixed interval to obtain the uniform coating of vegetable
oil on zinc phosphide powder to make it dust free.
2 The process of claim 1 where in the mixer is double cone blender
with internal flights in steel construction where there is no attrition.
3 The process of claim 2 where in the mixer rotational speed is
between 5 - 20 rpm.
4 The process of claim 1 where in the blending and coating operation is
carried out in dehumidified area.
5 The process of claim 4 where in the dehumidified area is between dew point of plus 5° C to minus 10° C.
6 The process of claim 1 where in the edible vegetable oils used are sunflower oil, soybean oil and olive oil.
7 The process of claim 1 where in the blending and coating
temperatures is maintained at or around 20° C - 60° C.
8 The process of claim 1 where in the coating is carried out in the ratio of 94.5 - 99.5 parts by wt of zinc phosphide powder to 0.5 - 5.5 parts by wtof edible vegetable oil.
9 The process of claim 1 where in the coating of zinc phosphide powder with edible vegetable oil is carried out at or around 2-6 hours.

10 The process of claim 1 where in the final packing of formulated zinc phosphide dust free is carried out in dehumidified area for safe handling of the product.