# The method for determining the indicator of the composition of the mixed aqueous solution of urea and ammonium nitrate

(57) Abstract:

The inventive method includes determining the following indicators of fertilizer composition: mass fraction of urea, mass fraction of ammonium nitrate, the total mass fraction of nitrogen contained in the aggregate of urea and ammonium nitrate, the ratio between the concentrations of urea and total content of urea and ammonium nitrate in the fertilizer. The definition of the indicators of the composition, in any case, is calculated by the formula in which values are assigned density and conductivity fertilizer at 25^{o}C and also with constant coefficients, whose values are defined for each indicator composition. Density and conductivity can be determined at any temperature in the range of 20-30

^{o}C, then recalculated to values corresponding to a temperature of 25

^{o}C. in the presence of fertilizer related substances assess the significance of each impurity related substance from the point of view of the necessary accounting and in the presence of significant impurities definition of the indicator composition is reduced to the definition of this indicator for a clean solution, which can be obtained from the solution of providesthe such a clean solution are determined by calculation. 4 C.p. f-crystals, 2 tab. The invention relates to analytical chemistry and can be used to determine the concentration of the main substances in liquid nitrogen fertilizers containing urea and ammonium nitrate in the form of their mixed aqueous solutions.There is a method of determining the indicator of the composition of the mixed aqueous solution of urea and ammonium nitrate, including the definition of its two characteristic parameters, including density at a given temperature, with subsequent assignment to measure the composition of the solution the numerical value of the sum of a polynomial with constant coefficients

a

_{1}+ a

_{2}d + a

_{3}d

^{2}+ a

_{4}e + a

_{5}e

^{2}+ a

_{6}ed,

in which d and e are the characteristic parameters of the solution (La Chimicael'Industria, 1981, vol. 63, No. 3, p.163-166).In this known method as characteristic parameters of the mixed aqueous solution of urea and ammonium nitrate accept its density d and the refractive index e at the same temperature for 30

^{o}C.When using the dimension of density specified in the polynomial with constant coefficients, g/cm

^{3}: a

_{1}= 13,5523; a

_{2}= 139,36; a

_{3}= 0; a

_{4}= 0; a

_{5}= -85,2642; a

_{6}= 0 for the calculation of the mass/SUB> = 0 to calculate the mass fraction of nitrogen in the mixed aqueous solution of urea and ammonium nitrate.The value of the constant coefficients a

_{i}(taking into account initially adopted assumptions a

_{3}= a

_{4}= a

_{6}= 0) in the polynomial are chosen on the basis of experimental measurements of the density and refractive index at 30

^{o}C artificial liquid mixtures prepared by dissolving an accurate weight of urea, ammonium nitrate in water.One of the disadvantages of this method is its unsuitability for the automatic analysis of the composition of liquid nitrogen fertilizer because of problems with automatic remote transmission of the results of measurements of the refractive index, the distortion which is not valid.Another disadvantage is the need to stabilize the temperature of the solution at 30

^{o}C when measuring its density and refractive index.Another disadvantage of ignoring the admixtures of other substances in the mixed aqueous solution of urea and ammonium nitrate, which affect the density and the refractive index of the solution, which reduces the accuracy of the analysis of its composition.The practice of industrial testifies to the presence of impurities of various substances from a few hundredths of a percent to several percent. It can be trace elements - molybdenum, cobalt, zinc, copper, manganese in the form of their salts, of complexions or chelate compounds, add nitrogen fertilizer to increase crop yields. Some substances are mixed in an aqueous solution of urea and ammonium nitrate in the form of production of impurities along with the original fluids entering the mixing in obtaining fertilizers (ammonia, carbon dioxide, biuret, mineral oil together with a solution of urea, nitric acid or ammonia, ammonium sulfate - ammonium nitrate solution). To reduce the corrosivity of Cam solutions to them often specially add the ammonium phosphates in the amount of 0.2 wt.% in terms of P

_{2}O

_{5}and up to 0.1 wt.% free ammonia.Thus there is a method of analysis applies to the entire range of liquid nitrogen fertilizers based on urea and ammonium nitrate containing various impurities, empirical dependences obtained in the pure model compounds that do not contain any side of impurities in addition to the main components (urea, ammonium nitrate and water).Higher accuracy has other>in the polynomial. It is the most similar set of features to the proposed method and selected as the prototype method. This method of determining the indicator of the composition of the mixed aqueous solution of urea and ammonium nitrate includes the definition of its two characteristic parameters, including density at 25

^{o}C, followed by the assignment of indicator solution composition numeric values, deviating by no more than 1.2% of the sum of a polynomial with constant empirical coefficients a

_{1},...a

_{6}< / BR>

a

_{1}+ a

_{2}d + a

_{3}d

^{2}+ a

_{4}e + a

_{5}e

^{2}+ a

_{6}de,

in which d and e are the characteristic parameters of the solution (RF Patent N 1 644026, CL G 01 N 31/22, 01.01.93 (20.12.88)).Defined by the indicator composition is the content of nitrogen in the fertilizer. Another characteristic parameter in addition to the density of the solution at 25

^{o}C d is the concentration of ammonium nitrate in solution e, determined by titrimetric method. For constant coefficients a

_{i}intervals are specified allowable values (for example, when the optimal value of a

_{1}= -1,34579 10

^{2}allowed the extreme values of a

_{1}= -1,3448 10

^{2}and a

_{1}= -1,3468 10

^{2}).When using the edge of the Oia nitrogen and greatest is 2.2%. Recommended optimal values of the coefficients a

_{1},...a

_{6}, where the average relative error is minimum and equal to 1.0%. Thus the nitrogen content calculated using a six-membered rings of polynomial using extreme valid values a

_{i}differs by no more than 2.2-1 = 1,2% (in the smaller and larger side) from the calculation results when the optimal values of a

_{i}.The disadvantages of the prototype method, as previously mentioned how similar are:

unsuitability for the automatic analysis of the composition of the solution;

the need to stabilize the temperature of the sample at a given level (25

^{o}C);

the increase in the error of the method in the analysis of a solution containing impurities.The objective of the invention is a method of analysis of the composition of liquid nitrogen fertilizers based on urea and ammonium nitrate that can be automated, requiring no additional time to stabilize the temperature of the sample and retain its accuracy in the presence of fertilizer impurities.This problem is solved due to the fact that in the known method of determining the indicator of the composition of the mixed aqueous solution of urea is oC, followed by the assignment of indicator solution composition numeric values, deviating by no more than 1.2% of the sum of a polynomial with constant empirical coefficients a

_{1},...a

_{6}< / BR>

a

_{1}+ a

_{2}d + a

_{3}d

^{2}+ a

_{4}e + a

_{5}e

^{2}+ a

_{6}de, (1)

in which d and e are the characteristic parameters of the solution,

according to the invention as another characteristic parameter e solution is taken as its specific electropotence at 25

^{o}C.In the case of dimension kg/m

^{3}for the density and Cm/m for conductivity used the following optimal value of the constant coefficients:

a

_{1}= -1,22854 10

^{3}; a

_{2}=2,17796; a

_{3}=9,0674810

^{-4}; a

_{4}=-7,40006; a

_{5}=5,63361 10

^{-2}; a

_{6}=2,9765810

^{-3}- to determine the mass fraction of urea, %;

a

_{1}= 3,5559510

^{2}; a

_{2}= -8,1515710

^{-1}; a

_{3}=4,2834110

^{-4}; a

_{4}=5,60228; a

_{5}=-3,5978810

^{-2}; a

_{6}= -2,60211 10

^{-3}-to determine the mass fraction of ammonium nitrate;

a

_{1}= -4,48877 10

^{2}; a

_{2}=7,3109710

^{-1}; a

_{3}=-2,73238 10

^{-4}; a

_{4}=-1,49242; a

_{5}= 1,36969 10

^{-2}; a

_{6}= 4,78234 10

^{-4}to determine the total mass fraction of nitrogen, SUP>; a

_{4}=-9,85402 10

^{-2}; a

_{5}=5,44829 10

^{-4}; a

_{6}=4,72439 10

^{-5}- to determine the ratio of x

_{K}/(x

_{K}+x

_{A}), where x

_{K}x

_{A}- mass fraction of urea and ammonium nitrate.If this new value of the constant coefficients a

_{i}in the case of other dimensions of variables and/or determining other, not listed above composition, are simple arithmetic calculation, based on the above values of the constant coefficients a

_{i}.Suppose you want as an indicator of the composition of the solution to determine the amide component of the nitrogen, i.e., the mass fraction of nitrogen introduced into a solution of urea, in percent, using the dimension density g/cm

^{3}instead kg/m

^{3}and conductivity Cm/m will Produce the necessary recalculation of the coefficients a

_{i}to calculate the mass fraction of urea in the new constant coefficients, taking into account the given conditions:

a

_{1}= (-1,22854 10

^{3})0,46666 =-5,73310 10

^{2};

a

_{2}= 2,17796 0,4666610

^{3}= 1,01637 10

^{3};

a

_{3}= -9,06748 10

^{-4}0,46666 10

^{6}= -4,23143 10

^{2};

a

_{4}= -7,400060,46666 =-3,45331;

a

_{5}=5,63361 10

^{-2}0,46666 = 2 is I calculate the indicators of the composition of the mixed aqueous solution of urea and ammonium nitrate can be used not only different values of the constant coefficients a

_{i}in the polynomial, but other functional dependencies have different structure (more complex or simpler), expressed either analytically, or in the form of graphs, charts, tables, provided that the found values of the indicators of the composition deviates by no more than 1.2% of the calculation of the polynomial (1) with a given constant coefficients a

_{i}.Thus, the role of the polynomial with the given constant coefficients a

_{i}boils down to the job of a narrow "corridor" reliable values defined indicator of the composition of the solution, changing depending on the characteristic parameters d and e. However, assigning the desired indicator composition of a numerical value equal to the result of evaluating the polynomial with the given constant coefficients a

_{i}is preferred before applying any other functional dependencies or even the same polynomial, but with different constant coefficients a

_{i}.This method of analysis of the composition of the mixed aqueous solution of urea and ammonium nitrate based on experimental studies of density and conductivity 45 different synthetic mixtures prepared by dissolving accurate, the wt.%, ammonium nitrate - 20-54 wt.%.Replacement of the characteristic parameter of the solution, the concentration of ammonium nitrate, which is determined by titrimetric method (as in method-prototype), or refractive index of the solution (as in method-analogue) on the conductivity of the solution - does the method of analysis according to the invention is more suited for automation, because the instrument without human intervention measurement of the electrical conductivity of the solution and remote transfer of evidence do not pose much of a problem.In addition, according to the invention the density and conductivity of the mixed water solution of urea and ammonium nitrate at 25

^{o}C used as characteristic parameters d and e are determined after and on the basis of the results of measuring the density (d

_{t}) and conductivity e

_{t}solution at all temperatures, respectively, t

_{d}and t

_{e}in the interval 20-30

^{o}C with the d parameter is assigned a value deviating by no more than 1 kg/m

^{3}from the results of the formula

d = d

_{t}+ 0,7 (t

_{d}-25), (2)

and the characteristic parameter e is assigned a value, deviating no more than Camelie the limits of deviation for the density 1 kg/m

^{3}and conductivity of 0.2 Cm/m is provided in case of use of the formulas (2) and (3) other species or charts and tables, giving slightly different results. Error 1 kg/m

^{3}or 0.2 Cm/m may cause, for example, additional error of 0.05 wt.% when determining the total mass fraction of nitrogen.Due to the fact that for the determination of characteristic parameters of solution d, e use measurements of the density of d

_{t}and conductivity e

_{t}solution at any temperature t

_{d}, t

_{e}in the interval 20 - 30

^{o}C, there is no need to stabilize at a certain temperature level of the analyzed solution. In the end, will decrease the time spent on the analysis in General. In addition, the temperature at which measured both the physical properties of the solution, should not be the same, which facilitates the automation of the analysis, because the sensor density and conductivity are usually installed in various sections of the pipeline, often with uneven temperature.However, the accuracy of the metric structure of liquid nitrogen fertilizer influence present in it traces of other, related substances (pommecythere mixed aqueous solutions of urea and ammonium nitrate permanent impurities related substances pre-and one day before the beginning of systematic analyses assess the significance of the impurity of each of the i-th accompanying substances from the point of view of the necessity of including it in further analysis solutions why compare when 25

^{o}C, on the one hand, the density of D

_{i}and/or conductivity E

_{i}an aqueous solution containing an impurity of only one of the i-th concomitant substance with mass fractions Y

_{i}and, on the other hand, the density of d

_{o}and/or conductivity e

_{0}another solution that does not contain any impurities, but in which the concentration of urea and ammonium nitrate are exactly the same as in the first solution, then calculate the empirical constant B

^{d}

_{i}characterizing the degree of influence of impurities of the i-th auxiliary substance to the density of the analyzed solutions, according to the formula

< / BR>

and/or empirical constant B

^{e}

_{i}characterizing the degree of influence of impurities of the i-th auxiliary substances in electrical conductivity of solutions analyzed, according to the formula

< / BR>

then determine the maximum possible expected mass fraction of impurities of the i-th auxiliary substances Y

_{i,max}in the analyzed solutions and, based on the dimensions of kg/m

^{3}for the density, Cm/m for conductivity, wt.% for mass fractions of impurities (Y

_{i,max}, Y

_{i}), verify the following inequalities:

< / BR>

< / BR>

in the future, Rimes i-th auxiliary substances ignore, i.e. consider insignificant, if at the same time when both of inequality.The simultaneous conditions (6) and (7) ensures that ignoring impurities of the i-th auxiliary substances will cause dismissive small additional error in determining the composition of the solution. For example, as a result of ignoring this mixture when determining the total mass fraction of nitrogen instead of 32.0% can get values from 31,95 to 32,05%, which is quite acceptable.Thus, conditions (6) and (7) allow to estimate the impact of possible impurities related substances on the accuracy of the method of analysis of the composition of the mixed aqueous solution of urea and ammonium nitrate, and to single out the significant impurities related substances that need to be considered when analysing the composition of the solution.An additional improvement of this method of analysis is that according to the invention in the presence of the analyzed mixed aqueous solution of urea and ammonium nitrate significant impurities related substances determination of the indicator of the composition of the solution with impurities is reduced to the definition of the indicator composition equivalent in the content of basic substances clean icestone water.For example, a mixed aqueous solution of urea and ammonium nitrate may contain 0.5 wt.% free ammonia and 0.3 wt.% carbon dioxide, which can affect the density and conductivity of the solution.If you weigh a sample of the analyzed solution, then atdot from her air of NH

_{3}and CO

_{2}after that add water to the sample in an amount necessary to restore the original weight of the sample, then get a clean solution, which is equivalent to the original solution with impurities content of urea and ammonium nitrate. The net solution obtained from a solution with impurities resulting from the replacement of the latter is equivalent to the mass quantities of water, while the mass fraction of urea and ammonium nitrate remained unchanged. Therefore, the indicator composition on the basic substances, calculated for equivalent net solution after determining its density and conductivity at 25

^{o}C, will be equal to the index of the composition of the initial solution with impurities NH

_{3}and CO

_{2}.In this way it is possible to avoid the negative impact of impurities on the accuracy of the analysis of the composition of the mixed aqueous solution of urea and ammonium nitrate p the initial solution is not always possible to implement in practice especially when impurities are not easily OTDELENIE gases, and any salt. The need for such a transformation of the original test solution is no longer, if according to the invention additionally quantify the content of relevant impurities related substances analyzed in a mixed aqueous solution of urea and ammonium nitrate and characteristic parameters d and e are equivalent in the content of basic substances clean solution are determined by calculation depending on the mass fractions Y

_{i}significant impurities, the density of d

_{t}and conductivity e

_{t}the analyzed solution at any temperature t

_{d}and t

_{e}accordingly, taken from the interval 20 - 30

^{o}C, the formula

< / BR>

< / BR>

where

n - the number of significant impurities in the sample solution;

B

^{d}

_{i}and B

^{e}

_{i}- pre-installed by the formulas (4) and (5) empirical constants for each of the i-th accompanying matter.Thus, the definition of the indicator composition of the solution with impurities is reduced to the definition of the indicator composition equivalent in the content of basic substance of clean solution, characteristic parameters d and e which easily operauonal e

_{t}initial solution with impurities and mass fractions y

_{i}admixtures. Thanks to this way of analysis of the composition of the mixed aqueous solution of urea and ammonium nitrate according to the invention retains its accuracy and in the presence of admixtures of other substances. In the end, this method can be applied for analysis of the composition of the industrial liquid nitrogen fertilizers based on urea and ammonium nitrate, often containing significant impurities related substances.For the application of the proposed method of analysis necessary condition is the preliminary determination of mass fractions y

_{i}impurities related substances. However, this is not in practice an additional complication of the analysis procedure as in the production of technical specifications for the manufactured liquid nitrogen fertilizer necessarily involve the use of appropriate chemical methods for determination of mass fractions of significant impurities in the product, regardless of which analysis method is used in the following for determination of urea and ammonium nitrate. For example, the content of free ammonia and ammonium phosphates in liquid nitrogen fertilizer specially controlled and todaywell fertilizer storage tanks from plain carbon steel.In some cases, when determining the concentration of significant impurities can be applied indirect methods. For example, the addition of ammonia or nitric acid in the mixed aqueous solution of urea and ammonium nitrate can be estimated by the value of the pH of a solution using empirical relationships linking the pH value of the solution with mass fraction of NH

_{3}or HNO

_{3}in the solution.Example 1. Measured at 25

^{o}C the density and conductivity of the mixed water solution of urea and ammonium nitrate, containing no significant admixtures of other substances

d = 1321 kg/m

^{3}; e = 11,20 Cm/mBy the formula (1) determine the total mass fraction of nitrogen in solution

x

_{N}= -4,48877 10

^{2}+ 7,31097 10

^{-1}1321 - 2,73238 10

^{-4}1321

^{2}- 1,49242 11,20 + 1,36969 10

^{-2}11,20

^{2}+ 4,78234 10

^{-4}1321 11,20 = -448,877 + 965,779 - 476,811 - 16,715 + 1,718 + 7,076 = 32,17 wt.%.Determine the ratio of x

_{K}/(x

_{K}+ x

_{A}):

x

_{K}/(x

_{K}+ x

_{A}) = -8,55101 + 1,7660510

^{-2}1321 - 8,03100 10

^{-6}1321

^{2}- 9,85402 10

^{-2}11,20 + 5,44829 10

^{-4}11,20

^{2}+ 4,72439 10

^{-5}1321 11,20 = -8,55101 + 23,329 - 14,014 - 1,104 + 0,068 + 0,69898 = 0,428.From here you can also find

x

_{K}/x

_{A}= 0,428/(1 - 0,428) = 0,748.Example 2. Measurement is

^{o}C (t

_{e}= 30

^{o}C, e

_{t}= 12,4 Cm/m) mixed aqueous solution of urea and ammonium nitrate, which does not contain impurities.By the formulas (2) and (3) v characteristic parameters of the solution, i.e. its density d and the electric conductivity e at 25

^{o}C

d = d

_{t}+ 0,7 (t

_{d}- 25) = 1324,5 + 0,7(20 - 25) = 1321 kg/m

^{3};

e = e

_{t}- (0,085 + 0,125 e

_{t}) (t

_{e}- 25) = 12,4 - (0,085 + 0,0125 12,4) (30 - 25) = 11,2 Cm/mBy the formula (1) determine the mass fraction of urea in solution

x

_{K}= -1,22854 10

^{3}+ 2,17796 1321 - 9,06748 10

^{-4}1321

^{2}-7,40006 11,2 + 5,63361 10

^{-2}11,2

^{2}+ 2,97658 10

^{-3}1321 11,2 = -1228,54 + 2877, 085 - 1582, 312 - 82,881 + 7,067 + 44,039 = 34,46%.Defined mass fraction of ammonium nitrate in solution

x

_{A}= 3,55595 10

^{2}8,15157 10

^{-1}1321 + 4,28341 10

^{-4}1321

^{2}+ 5,60228 11,2 - 3,59788 10

^{-2}11,2

^{2}- 2,60211 10

^{-3}1321 11,2 = 355,595 - 1076, 822 + 747,473 + 62,746 - 4,513 - 38,499 = 45,98%.Example 3. It is assumed that the systematic analysis of the composition of liquid nitrogen fertilizers containing impurities of ammonium phosphates (0.2 to 0.5% P

_{2}O

_{5}), ammonium sulphate (0.05 to 0.4 wt.%) and ammonia (0.03 to 0.1 wt.%).You need to evaluate impurities from the point of view of the necessity of taking them into account when analyzing the>.To get started, find empirical constants B

^{d}

_{i}and B

^{e}

_{i}for all these impurities.In table. 1 shows the experimental density data needed to determine the empirical constants B

^{d}

_{i}with regard to the substances from the above list.In experiment 1 (see tab.1) by the gravimetric method has been made test clean mixed aqueous solution of urea (x

_{K}= 27,86 wt.%) and ammonium nitrate (x

_{A}= 36,81 wt.%), i.e., a solution containing no significant admixture of foreign substances (Y

_{l}= 0). The measured density of this solution at 25

^{o}C - d

_{0}= 1247 kg/m

^{3}. In experiments 2 and 3 investigated the influence of the additive liquid complex fertilizers (HCS 10 : 34), containing a mixture of ortho-, pyro-, Tripoli and metropolitanates, to a mixed aqueous solution of urea and ammonium nitrate density (D

_{i}the last 25

^{o}C. In the preparation of samples in experiments 2 and 3 drew attention to the fact that the concentration of x

_{K}and x

_{A}remained the same as in experiment 1. Therefore, in experiments 2 and 3, samples of water were added in a smaller amount than in experiment 1, the magnitude of the added mass of the hinge housing 10:34. The concentration of the additive peress>= 1,367% P

_{2}O

_{5}. Based on these data, it is easy to calculate empirical constants B

^{d}

_{i}< / BR>

B

^{d}

_{i}= lg (1255,5/1247)/0,683 = 0,00432 to experience 2,

B

^{d}

_{i}= lg (1265,5/1247)/1,367 = 0,00468 for experience 3.Some discrepancies between the two values of B

^{d}

_{i}you can explain the inevitable experimental errors in the preparation of comparative sample solutions.In experiment 4 as an additive is used diammonium phosphate (DAP), and its concentration also counted in wt.% P

_{2}O

_{5}.In experiments 5 and 6 on the basis of data published in the open literature that are mapped between the density of water d

_{o}at 25

^{o}C and the density of an aqueous solution containing monoammonium phosphate (LFA) 14,64% P

_{2}O

_{5}. In this case, both samples are treated as aqueous solutions in which the concentration of urea and ammonium nitrate equal to zero. The value of the constant B

^{d}

_{i}= 0,00432 calculated in experiment 6 for the MAF, should be extended also to other forms of phosphates (HCS in experiments 2 and 3, DAP in experiment 4), since small differences in the results of the calculation of the B

^{d}

_{i}can be explained neizbeznim as the ammonium phosphates in the list of possible impurities placed first (i = 1), have B

^{d}

_{i}= 0,0043.In experiments 7 - 9 investigated the effect of supplementation of ammonium sulfate on the density of aqueous solutions (for compactness records of experiments, corresponding to the solutions without additives not included in the table. 1). When the impurity concentration from 3 to 45 wt. % the obtained values of the empirical constants B

^{d}

_{i}with difference from 0,00197 to 0,00225, which is quite acceptable and due to inevitable errors in the experiments.You should pay attention to the fact that, as experimentally confirmed in these experiments, the impurity salt nature increase the density of the aqueous solution of the same law, regardless of the content of urea and ammonium nitrate. Therefore, when determining the empirical constants B

^{d}

_{i}for salt impurities of nature (phosphate, ammonium sulfate), it is enough to compare the density of an aqueous solution of salt (D

_{i}with the density of pure water (d

_{o}) at 25

^{o}C, what can be done on the basis of data published in the open literature for aqueous solutions of various salts. For ammonium sulfate (i = 2) here accept B

^{d}

_{2}

_{/}= 0,0022.Similarly, HNO

_{3}accept B

^{d}

_{i}=0,0025.

d_{3}= -0,0035 (adding ammonia to clean water this constant would have the value -0,0018).

^{e}

_{i}with regard to the substances listed above.In the sixth column of the table. 2 shows the electrical conductivity (e

_{o}) sample pure mixed aqueous solution of urea and ammonium nitrate, and the seventh column - specific conductance (E

_{i}) solution with the same content of urea and ammonium nitrate, but in the presence of additives of different substances with mass fractions Y

_{i}.In experiments 1 - 8 defined constant B

^{e}

_{i}for phosphate type HCS 10:34; its value varies in the interval from -1,171 to -1,440 due to experimental errors. Received for utility services 10:34 averaged value of the constant B

^{e}

_{1}= -1,3.If instead HCS 10:34 as a corrosion inhibitor to apply phosphate (DAP), you should use B

^{e}

_{1}= of-2.1 (experiments 9 and 10).When evaluating the effect of the additive su is s taken B

^{e}

_{2}= -0,45 (experiment 11).The admixture of ammonia (i = 3) weak or no effect on the conductivity of solutions of Cam (experiments 12 - 15). Some scatter of the values of B

^{e}

_{i}about zero is associated with the error of the experiment, and not with a certain regularity. Accept B

^{e}

_{3}= 0.For nitric acid taken, averaged, and rounded the value of the constant B

^{e}

_{i}= -0,5 (experiments 16, 17). In the experience of 16 is not installed concentrations of urea and ammonium nitrate (which, incidentally, does not matter), since both samples were prepared from the same mixed aqueous solution, divided equally, then adding one-half solution of nitric acid, and in another - the equivalent mass of water. Therefore, the condition of equal concentrations of the main substances in the samples observed.It is now possible to evaluate the significance of these impurities

B

^{d}

_{1}= 0,0043; B

^{e}

_{1}= of-2.1 (DAP); Y

_{I,max}=0.5 wt.% /0,0043/>(1,710

^{-4}/0,5 = 0,00034); /-2,1/> (0,05/0,5 = 0,1).B

^{d}

_{2}= 0,0022; B

^{e}

_{2}= 0,00034; Y

_{2,max}= 0.4 wt.% /0,0022/ >(1,710

^{-4}/0,4 = 0,00042); /-0,45/>(0,05/0,4 = 0,125).B

^{d}

_{3}= -0,0035; B

^{e}

_{3}is vremenno for each of the three impurities, all admixtures should be considered significant.Example 4. The analysis of the composition of liquid nitrogen fertilizers based on urea and ammonium nitrate containing as impurities DAP (i = 1), ammonium sulfate (i = 2) and ammonia (i = 3). According to preliminary data of example 3, all the impurities are significant.Using traditional techniques, determine the mass fraction Y

_{i}related substances:

Y

_{1}= 0,33 wt.% P

_{2}O

_{5}.Y

_{2}= 0,35 wt.% (NH

_{4})

_{2}SO

_{4};

Y

_{3}= 0.09 wt.% NH

_{3}.At temperature t

_{d}= 20,3

^{o}C measured density fertilizer

d

_{t}= 1330 kg/m

^{3}.At temperature t

_{e}= 21,0

^{o}C measured conductivity fertilizer

e

_{t}= at 9.53 Cm/mFind the characteristic parameters d and e are equivalent fertilizer (containing main substances) net mixed aqueous solution of urea and ammonium nitrate, using empirical constants B

^{d}

_{i}and B

^{e}

_{i}as defined in example 3, and formula (8) and (9)

< / BR>

.Based on thus determined, the characteristic parameters d = 1321 & e = 11,2, we calculate indicators SOS what learn

x

_{N}= 32,17 wt.% - total mass fraction of nitrogen (urea and ammonium nitrate);

x

_{K}(x

_{K}+x

_{A}) = 0,428, which implies x

_{K}/x

_{A}= 0,748;

x

_{K}= 34,46 wt.% - mass fraction of urea;

x

_{A}= 45,98 wt.% - mass fraction of ammonium nitrate. 1. The method for determining the indicator of the composition of the mixed aqueous solution of urea and ammonium nitrate, including the definition of its two characteristic parameters, including density at 25

^{o}With, followed by the assignment of indicator solution composition numeric values, deviating by no more than 1.2% of the sum of a polynomial with constant empirical coefficients and

_{1}- a

_{6}according to the formula

and

_{1}+ a

_{2}d + a

_{3}d

^{2}+ a

_{4}e + a

_{5}e

^{2}+ a

_{6}d e,

in which d and e are the characteristic parameters of the solution,

characterized in that, as a characteristic parameter e solution is taken as its specific conductivity at 25

^{o}With when using the dimension kg/m

^{3}for the density and Cm/m for conductivity accept the following optimal value of the constant coefficients: either a

_{1}= -1,22854 10

^{3};

_{2}= 2,17796; and

_{3}= -9,06748 10

^{-}

^{1= 3,55595 102;2= -8,15157 10-1;3= 4,28341 10-4;4= 5,60228; and5= -3,59788 10-2;6= -2,60211 10-3- to determine the mass fraction of ammonium nitrate% or1= -4,48877 102;2= 7,31097 10-1;3= -2,73238 10-4;4= -1,49242; and5= 1,36969 10-2;6= 4,78234 10-4to determine the total mass fraction of nitrogen in the urea and ammiachnoi nitrate,% or as1= -8,55101 and2= 1,76605 10-2;3= -8,03100 10-6;4= -9,85402 10-2;5= 5,44829 10-4;6= 4,72439 10-5- to determine the ratio of xTO/ (xTO+ xAND), where xTOand xAND- mass fraction, respectively, of urea and ammonium nitrate, with new values of the empirical constant coefficients andiin the case of other dimensions of variables and/or determining other not listed the indicators of the composition, are simple algebraic calculation, based on the given values of constant coefficients andi.2. The method according to p. 1, characterized in that protostelium as characteristic parameters d and e, determine after and on the basis of the results of measurement of density dtand conductivity etsolution at all temperatures, respectively, tdand tein the interval 20 - 30oWith characteristic parameter density d assign a value deviating by no more than 1 kg/m3from the result of the formula 2d = dt+ 0,7 (td- 25),and the characteristic parameter for conductivity E. assign a value deviating by no more than 0.2 Cm/m from the result of the formula 3e = et- (0,085 + of 0.0125 et) (te- 25).3. The method according to p. 1, characterized in that in the presence of repeatedly analyzed mixed aqueous solutions of urea and ammonium nitrate permanent impurities related substances pre-and one day before the beginning of systematic analyses assess the significance of the impurity of each of the i-th accompanying substances from the point of view of the need for its consideration in further analyses of the solutions, which match with the 25oWith, on the one hand, the density of Diand/or conductivity Eian aqueous solution containing an admixture of only one of the i-th concomitant UB>0another solution that does not contain any impurities, but in which the concentration of urea and ammonium nitrate are absolutely the same as in the first solution, then calculate the empirical constant Bdicharacterizing the degree of influence of impurities of the i-th auxiliary substance to the density of the analyzed solutions, according to the formula 4< / BR>and/or empirical constant Beicharacterizing the degree of influence of impurities of the i-th auxiliary substances in electrical conductivity of solutions analyzed, according to the formula 5< / BR>then determine the maximum possible expected mass fraction of impurities of the i-th auxiliary substances Yi.maxin the analyzed solutions, and based on the dimensions of kg/m3for density, Cm/m for conductivity, wt.% for mass fractions of impurities (Yi.max, Yi), check the inequality 6 and 7< / BR>< / BR>in the future when conducting systematic analyses of mixed aqueous solutions of urea and ammonium nitrate admixture of the i-th auxiliary substances ignored, i.e., consider insignificant, if at the same time when both of inequality.4. Noah nitrate significant impurities related substances determination of the indicator of the composition of the solution with impurities is reduced to the definition of the indicator composition equivalent in the content of basic substance of clean solution, which can be obtained from a solution with impurities, if the latter is replaced with the equivalent mass quantities of water.5. The method according to p. 4, characterized in that it further quantify the content of relevant impurities related substances analyzed in a mixed aqueous solution of urea and ammonium nitrate and characteristic parameters d and e are equivalent in the content of basic substances clean solution are determined by calculation depending on the mass fractions Yisignificant impurities, the density of dtand conductivity etthe analyzed solution at any temperature tdand teaccordingly, taken from the interval 20 - 30oWith, by formulas 8 and 9< / BR>< / BR>where n is the number of significant impurities in the sample solution;Bdiand Bei- pre-installed by the formulas (4) and (5) empirical constants for each of the i-th auxiliary substances. }

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