Fertilizers mineral

w - w
5= —I 00<0.95,
(15)
8
Machine Translated by Google

---

GOST 8.613-2012
Features of the effect of infrared radiation on wet substances
160
Potassium sulfate and middlings
5
70
—
weights, g
10
Auto
90
135
material, temperature and shape of the filament body.
30 min
Ammonium nitrate
90
9
Halogen heater
Auto
80
2.5
80
—
Table A.1 - Drying regimes for measuring the mass fraction of moisture in some mineral fertilizers using IKTG moisture meters
with various infrared emitters
—
Annex A
(mandatory)
Ammophos
Auto
Drying
stop criterion
3
180
Sources of IR radiation are divided into light and dark IR emitters with a filament body in glass and metal shells. Light
include IR emitters, in which the temperature of the heating body is more than 1000 ° C, and in the emitted spectrum a
significant proportion is visible radiation. These are incandescent lamps; lamp emitters, for example, halogen; gas-discharge
arc lamps; electric emitters (mirror lamps). For dark IR emitters, among which the most common electric emitters with a ceramic
or metal sheath, the temperature of the filament body is less than 1000 ° C, and the visible radiation in the spectrum is fractions
of a percent.
Superphosphate
180
120
Drying temperature, °C
ten
20 minutes
10
170
Azofoska
Auto
60
100
Heater in a ceramic
sheath
5
160
—
When creating moisture meters based on the NIR spectroscopy method (also called IR photometric moisture meters or
NIR spectrometers), incandescent lamps are used as a source of study, and light filters are used to isolate narrow wavelengths
in the wavelength range from 1400 to 2200 nm. In the near IR region from 1400 to 2200 nm, water molecules have an absorption
band with a maximum in the range of 1950–1960 nm, which corresponds to composite frequencies, as well as an absorption
band in the region of 1430–1450 nm, which corresponds to the first overtones of water molecules. To obtain greater stability of
the output signal of the NIR moisture meter, a two-wave measurement scheme is usually used, according to which the signal
is the ratio of the intensities measured at the analytical wavelength (one of the absorption bands by water molecules) and the
reference wavelength (the wavelength lying outside the absorption band by molecules water). The use of the ratio of two
signals from the flows of the reference and measuring channels makes it possible to reduce the influence of the instability of
the photodetector and the source of NIR radiation, the physicochemical characteristics of the analyzed substance, and also
somewhat reduce the influence of its bulk density. When creating moisture meters based on the IR TG method, all possible
types of emitters are used, since effective heating
of the analyte as a result of its absorption of IR radiation energy is achieved when the maximum spectral density of the
incident IR radiation coincides with the maximum absorption band of the irradiated analyte. Heating a substance under the
influence of IR radiation can lead not only to the removal of moisture, but also to various physicochemical transformations in it.
Therefore, the use of the IR TG method for measuring the mass fraction of moisture requires an assessment of the effect of
IR radiation on the material of the analyzed sample. The parameters of the mode for measuring the mass fraction of moisture
in a particular mineral fertilizer and middling product by the IR TG method (temperature and drying time, sample weight) should
be selected for IR TG moisture meters of a particular type.
Magnesia
180
200
15 minutes
180
Potassium chloride and middlings
80
160
Weight
3
IR radiation is the region of the optical range of electromagnetic radiation. Its spectrum ranges from 760 nm to about 1
mm. Infrared emitters differ in
the ways of generating radiation, the range of the IR spectrum, ma
Urea
Auto
50
The recommended drying parameters and sample weight when measuring the mass fraction of moisture in mineral
fertilizers and middlings on IR TG moisture meters with various types of heaters are given in Table A.1.
Fertilizer name
5
Machine Translated by Google

---