Method for analyzing total nitrogen content in copper concentrate

Abstract

The invention relates to the technical field of chemical detection, in particular to a method for analyzing the content of total nitrogen in copper concentrate. 2, under the acidic condition, oxidizing nitrite in the copper concentrate sample to be detected into nitrate by using potassium permanganate; then excessive reduced iron powder is added, and nitro nitrogen is reduced into amino nitrogen; adding concentrated sulfuric acid and an accelerator, heating, and digesting and boiling the organic nitrogen at high temperature to convert the organic nitrogen into amino nitrogen; adding a sodium hydroxide solution, converting ammonium nitrogen into ammonia gas under an alkaline condition, distilling the ammonia gas, and absorbing the ammonia gas by using a boric acid solution; and finally, titrating the boric acid solution absorbing the ammonia gas by using a standard hydrochloric acid solution so as to calculate the total nitrogen content in the copper concentrate sample to be detected. By adopting the method for analyzing the total nitrogen content in the copper concentrate, expensive equipment can be prevented from being purchased, the analysis speed is high, the efficiency is high, and good accuracy is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical detection, and in particular to a method for analyzing the total nitrogen content in copper concentrate. Background Art

[0002] As the country's requirements for environmental protection become stricter, the emission standards for nitrogen oxides in smelting flue gas are becoming more and more stringent. Nitrogen oxides in smelting flue gas mainly come from raw materials, that is, copper concentrate, and the nitrogen oxide content of other auxiliary materials is relatively low. The nitrogen content in normal flotation copper concentrate is very low, but the current shortage of copper concentrate has caused many mines to be blended with copper-containing materials. The sources of many copper-containing materials are unknown, and some materials have a high nitrogen content. The use of such materials will cause the nitrogen oxides in the smelting acid tail gas to exceed the standard. If the content of nitrogen oxides in the flue gas is to be controlled to meet the national emission standards, it is necessary to know the nitrogen content in the raw materials, and then reduce the content of nitrogen oxides in the tail gas by mixing ingredients. However, the prior art does not have a specific analysis method for the nitrogen content in copper concentrate.

[0003] The existing methods for determining nitrogen mainly include the Kjeldahl method and the Dumas combustion method. The Kjeldahl method uses concentrated sulfuric acid to decompose nitrogen in organic matter to form ammonium sulfate, which is then distilled under alkaline conditions. The distilled ammonia is absorbed by boric acid, and finally the nitrogen content is calculated by titration with standard hydrochloric acid. It is suitable for determining the nitrogen content of organic matter or protein. This method is relatively cumbersome and slow to analyze. The Dumas combustion method is to burn at a high temperature of 900-1200°C, and the mixed gas is purified and reduced to generate nitrogen. The nitrogen content is then detected by a thermal conductivity detector. It is suitable for determining the nitrogen content of solid samples. The advantage is that the analysis speed is fast and no sample pretreatment is required. The nitrogen situation in copper concentrate is relatively complicated. There are both ammonia nitrogen and nitrate nitrogen, as well as some nitrite and organic nitrogen-containing substances. Because ammoniacal nitrogen begins to decompose at 100°C, there will be losses when using the Dumas combustion nitrogen determination method. In addition, copper concentrate contains a large amount of sulfur, and the sulfur dioxide produced by combustion will interfere with the determination of nitrogen. Therefore, the Dumas combustion nitrogen determination method is not suitable for the determination of nitrogen content in copper concentrate. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for analyzing the total nitrogen content in copper concentrate, which specifically includes the following contents:

[0005] A method for analyzing the total nitrogen content in a copper concentrate comprises the following steps: firstly oxidizing nitrite in a copper concentrate sample to be tested into nitrate with potassium permanganate under an acidic condition of pH <2; then adding an excessive amount of reducing iron powder to reduce nitro nitrogen into amino nitrogen; then adding concentrated sulfuric acid and an accelerator, and heating to digest and convert organic nitrogen into amino nitrogen at high temperature; then adding a sodium hydroxide solution, converting ammonium nitrogen into ammonia gas under alkaline conditions and distilling it out, and using a boric acid solution to absorb the ammonia gas; finally, titrating the boric acid solution that has absorbed the ammonia gas with a standard hydrochloric acid solution, thereby calculating the total nitrogen content in the copper concentrate sample to be tested.

[0006] Specifically, the method comprises the following steps:

[0007] S1, adding a copper concentrate sample with a mass of m and tertiary water to the reaction device to wet the surface of the sample, then adding potassium permanganate solution and mixing evenly to obtain a purple test system; the purpose of this step is to oxidize the water-soluble nitrite in the copper concentrate sample to convert it into nitrate;

[0008] S2, adding sulfuric acid solution to the test system obtained in S1, mixing evenly and letting it stand, waiting for the purple color in the test system to fade away, and then continuing to add potassium permanganate to the test system until the purple color no longer fades; the purpose of this step is to oxidize all nitrites in the sample into nitrates;

[0009] S3, using a special tool, adding reduced iron powder to the bottom of the liquid surface of the test system after the treatment in step S2 for redox reaction, and covering the mouth of the reaction device with a lid with holes to prevent splashing, after the violent reaction slows down, heating the reaction device at 110-120°C to keep the test system in a slightly boiling state and continue the redox reaction, after the reaction slows down, adding sulfuric acid solution to the test system until the reaction iron powder is completely reacted, and then cooling; the purpose of this step is: to convert nitrogen in nitrate into ammonium nitrogen by adding reduced iron powder, that is, convert pentavalent nitrogen into trivalent nitrogen;

[0010] S4, adding an accelerator and concentrated sulfuric acid to the system to be tested after treatment in step S3, mixing evenly, heating in an environment of 180-220° C. for 20-40 minutes, and then cooling; the purpose of this step is to convert organic nitrogen in the sample into ammonium nitrogen;

[0011] S5, remove the cover of the reaction device and rinse it with tertiary water, and return the rinse water to the system to be tested; transfer the system to be tested into the distillation device and then cool it; the purpose of this step is to convert all nitrogen elements into ammonium nitrogen and then transfer it to the distillation device for distillation;

[0012] S6, adding sodium hydroxide solution to the distillation apparatus described in step S5, adjusting the pH of the system to be tested to alkaline, then starting distillation, and passing the steam obtained by distillation into tertiary water added with a boric acid-indicator mixture through a conduit, and after the distillation is completed, a blue distillate containing dissolved ammonia is obtained; the purpose of this step is: under alkaline conditions, ammonium nitrogen is converted into ammonia and absorbed by the boric acid solution;

[0013] S7, flushing the conduit with tertiary water and returning the flushing water to the distillate; the purpose of this step is to wash the residual ammonia in the conduit and return it to the distillate;

[0014] S8, with a concentration of C HCl The distillate obtained in step S7 is titrated with the hydrochloric acid standard solution until the distillate changes from blue to reddish purple, and the consumed volume V of the hydrochloric acid standard solution is recorded; in this step, the mixed indicator of the distillate changes to blue under alkaline conditions, and changes to purple-red when titrated to neutral with the hydrochloric acid standard solution, indicating the end point;

[0015] S9, prepare a blank test according to steps S1-S9, except that the copper concentrate sample is not added to the blank group, the other steps are the same as the test group, and the consumption volume V0 of the hydrochloric acid standard solution in the blank group is recorded; the purpose of setting the blank group is to eliminate the influence of nitrogen in the reagent;

[0016] S10, calculate the nitrogen content according to the acid-base neutralization reaction, specifically according to the copper concentrate sample m, the concentration of the hydrochloric acid standard solution c HCl , as well as V and V0 to calculate the total nitrogen content in the copper concentrate sample.

[0017] Furthermore, the copper concentrate sample to be tested is a copper concentrate sample that has only been reduced and mixed but not dried.

[0018] Further, the sulfuric acid solution used in steps S2 and S3 is V H2SO4 :V H2O =1:(0.9-1.1) sulfuric acid solution.

[0019] Furthermore, the particle size of the reduced iron powder in step S3 is less than 100 mesh.

[0020] Furthermore, the accelerator in step S4 is a mixture of potassium sulfate, copper sulfate pentahydrate and selenium powder.

[0021] Furthermore, the mass ratio of potassium sulfate, copper sulfate pentahydrate and selenium powder is (90-110):(9-11):1.

[0022] Furthermore, the concentration of the sodium hydroxide solution in step S6 is 500-600 g / L, and the preparation method of the sodium hydroxide solution is: 100-120 g of analytical pure sodium hydroxide is slowly added into a container containing 200 ml of water under water cooling, and the mixture is continuously stirred.

[0023] Furthermore, the preparation method of the boric acid indicator solution in step S6 is: prepare the solution according to the ratio of pure boric acid: water: methyl orange-methylene blue indicator = 0.02g: 1mL: 0.002mL, then add a low concentration sodium hydroxide solution (concentration not more than 0.1000mol / L) to the solution to adjust the color of the solution to blue, and then add a standard hydrochloric acid solution to the solution until the solution turns purple-red.

[0024] Furthermore, the preparation method of the hydrochloric acid standard solution in step S8 is: use a measuring cylinder to measure 8.3 ml of concentrated hydrochloric acid and pour it into a 10-liter narrow-necked bottle, dilute to 10 L, shake well, and calibrate with a sodium carbonate reference reagent before use.

[0025] Furthermore, the method for calibrating the hydrochloric acid standard solution with the sodium carbonate reference reagent is as follows: firstly, accurately weigh a sodium carbonate reference substance with a mass of m1, dissolve it with grade tertiary water and then make up the volume, accurately pipette a certain amount of sodium carbonate solution, dilute it, and then add bromocresol green-methyl red mixed indicator to obtain a green solution; then, titrate the green with the prepared hydrochloric acid standard solution until the solution turns dark red, boil, cool, and continue to titrate until the solution turns dark red again, and at the same time, perform a blank test without adding the sodium carbonate reference substance, and calculate the concentration C of the hydrochloric acid standard solution. HCl :

[0026]

[0027] in:

[0028] m1 is the mass of sodium carbonate standard, in g;

[0029] V1 is the amount of hydrochloric acid standard solution, in ml;

[0030] V2 is the amount of hydrochloric acid standard solution consumed in the blank test, in ml;

[0031] M is the molar mass of 1 / 2Na2CO3 as the basic unit, M = 52.99 g / mol.

[0032] Furthermore, the method for calculating the total nitrogen content in the copper concentrate sample to be tested in step S10 is:

[0033]

[0034] in:

[0035] V is the volume of hydrochloric acid standard solution consumed when titrating the test solution, in mL;

[0036] V0 is the volume of hydrochloric acid standard solution consumed in the blank titration, in mL;

[0037] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0038] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0039] m is the mass of the copper concentrate sample to be tested, in g.

[0040] Beneficial effects of the present invention:

[0041] The present invention discloses a method for analyzing the total nitrogen content in a copper concentrate. Under an acidic condition of pH <2, potassium permanganate is used to first oxidize nitrite to nitrate. Under the condition of excessive reduced iron powder, nitro nitrogen is first reduced to amino nitrogen. Next, under the condition of concentrated sulfuric acid and an accelerator, organic nitrogen is digested at high temperature and converted into amino nitrogen. The liquid is then transferred to a distillation beaker, concentrated alkali is added, and ammonium nitrogen is converted into ammonia gas under alkaline conditions and distilled out. The ammonia gas is absorbed by a 2% boric acid solution. Finally, the absorption liquid is titrated with a standard hydrochloric acid solution to calculate the nitrogen content in the copper concentrate. Experimental verification shows that the method for analyzing the total nitrogen content in a copper concentrate disclosed by the present invention can avoid the purchase of expensive equipment, and has a fast analysis speed, high efficiency, and good accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of the reaction apparatus described in step S1;

[0043] Figure 2 A schematic diagram of a special tool used in step S3 to add reduced iron powder to the bottom of the liquid surface of the system to be tested;

[0044] Figure 3 Schematic diagram of the distillation apparatus used in step S6, wherein:

[0045] 1-conical flask; 2-rubber stopper; 3-glass air tube; 4-beaker; 5-absorption liquid; 6-absorbent cotton. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention content described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary as solutions to the invention described in the claims.

[0047] A method for analyzing total nitrogen content in copper concentrate specifically comprises the following steps:

[0048] S1, add a reaction device (flat bottom Kjeldahl flask, see attached Figure 1 ) adding a copper concentrate sample to be tested with a mass of m and third-grade water to wet the surface of the sample to be tested, and then adding a potassium permanganate solution and mixing evenly to obtain a purple test system; the copper concentrate sample to be tested is a copper concentrate sample that has only been reduced and mixed but not dried;

[0049] S2, add V to the system to be tested obtained in S1 H2SO4 :V H2O =1:(0.9-1.1) sulfuric acid solution, mix well and let stand, wait for the purple color in the test system to fade away, and then continue to add potassium permanganate to the test system until the purple color no longer fades;

[0050] S3, use special tools (see attached Figure 2 ), add reduced iron powder with a particle size of less than 100 mesh to the bottom of the liquid surface of the system to be tested after the treatment in step S2 to carry out redox reaction, and cover the mouth of the reaction device with a lid with holes to prevent splashing. After the violent reaction slows down, heat the reaction device at a temperature of 110-120°C to keep the system to be tested in a slightly boiling state and continue the redox reaction. After the reaction slows down, add V H2SO4 :V H2O =1:(0.9-1.1) sulfuric acid solution, until the iron powder reacts completely, and then cool;

[0051] S4, adding an accelerator and concentrated sulfuric acid to the test system after treatment in step S3, mixing evenly, heating in an environment of 180-220° C. for 20-40 minutes, and then cooling; the accelerator is a mixture of potassium sulfate, copper sulfate pentahydrate and selenium powder in a mass ratio of (90-110):(9-11):1;

[0052] S5, remove the cover of the reaction device and rinse with grade tertiary water, and return the rinse water to the system to be tested; transfer the system to be tested into the distillation device and then cool it;

[0053] S6, to the distillation apparatus described in step S5 (refer to attached Figure 3 ) to adjust the pH of the system to be tested to alkaline, then start distillation, and use a conduit to pass the steam obtained by distillation into tertiary water added with a boric acid-indicator mixture. After the distillation is completed, a blue distillate containing dissolved ammonia is obtained;

[0054] The concentration of the sodium hydroxide solution is 500-600g / L. The preparation method of the sodium hydroxide solution is: 100-120g of analytical pure sodium hydroxide is slowly added into a container containing 200ml of water under water cooling, and the mixture is continuously stirred; the preparation method of the boric acid indicator solution is: a solution is prepared according to the ratio of pure boric acid: water: methyl orange-methylene blue indicator = 0.02g: 1mL: 0.002mL, and then a low concentration sodium hydroxide solution (concentration is not more than 0.1000mol / L) is dripped into the solution to adjust the color of the solution to blue, and then a hydrochloric acid standard solution is dripped into the solution until the solution turns purple-red;

[0055] S7, flushing the conduit with tertiary water and returning the flushing water to the distillate;

[0056] S8, with a concentration of C HCl The distillate obtained in step S7 is titrated with the hydrochloric acid standard solution until the distillate changes from blue to reddish purple, and the consumed volume V of the hydrochloric acid standard solution is recorded;

[0057] The preparation method of the hydrochloric acid standard solution is: use a measuring cylinder to measure 8.3 ml of concentrated hydrochloric acid and pour it into a 10-liter narrow-necked bottle, dilute to 10L, shake well, and calibrate with a sodium carbonate reference reagent before use. The method of calibrating the hydrochloric acid standard solution with the sodium carbonate reference reagent is: first accurately weigh a sodium carbonate reference substance with a mass of m1, dissolve it with grade tertiary water and then make up the volume, accurately transfer a certain amount of sodium carbonate solution and dilute it, then add bromocresol green-methyl red mixed indicator to obtain a green solution; then, use the prepared hydrochloric acid standard solution to titrate the green until the solution turns dark red, boil, cool, and continue to titrate until the solution turns dark red again, and at the same time, perform a blank test without adding the sodium carbonate reference substance, and calculate the concentration C of the hydrochloric acid standard solution. HCl :

[0058]

[0059] in:

[0060] m1 is the mass of sodium carbonate standard, in g;

[0061] V1 is the amount of hydrochloric acid standard solution, in ml;

[0062] V2 is the amount of hydrochloric acid standard solution consumed in the blank test, in ml;

[0063] M is the molar mass of 1 / 2Na2CO3 as the basic unit, M = 52.99 g / mol;

[0064] S9, prepare a blank test according to steps S1-S9, except that the copper concentrate sample to be tested is not added to the blank group, the other steps are the same as the test group, and the consumption volume V0 of the hydrochloric acid standard solution of the blank group is recorded;

[0065] S10, according to the copper concentrate sample m, the concentration of the hydrochloric acid standard solution c HCl , as well as V and V0 to calculate the total nitrogen content in the copper concentrate sample to be tested:

[0066]

[0067] in:

[0068] V is the volume of hydrochloric acid standard solution consumed when titrating the test solution, in mL;

[0069] V0 is the volume of hydrochloric acid standard solution consumed in the blank titration, in mL;

[0070] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0071] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0072] m is the mass of the copper concentrate sample to be tested, in g.

[0073] Example 1

[0074] A method for analyzing total nitrogen content in copper concentrate comprises the following steps:

[0075] (1) First, weigh the original copper concentrate sample and put it into the reaction device using a special tool. Add 2 ml of grade 3 water to the reaction device, shake the reaction device to make the sample evenly wetted, add 1 ml of potassium permanganate solution to the reaction device, shake the reaction device again, and make two blanks along with the experiment; then slowly add 10 drops of V to the reaction device using a dropper H2SO4 :V H2O =1:1 sulfuric acid solution, keep rotating the reaction device, then leave it for 5 minutes, wait for the color of potassium permanganate to fade, and then add potassium permanganate until the purple color no longer fades;

[0076] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O =1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when sulfuric acid is added and no gas is generated.

[0077] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0078] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0079] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0080] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0081] (7) Calculate the total nitrogen content in copper concentrate.

[0082]

[0083] in:

[0084] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0085] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0086] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0087] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0088] m is the mass of the sample, in g.

[0089] The C HCLThe determination method is as follows: First, accurately weigh 0.0400g of sodium carbonate reference material that has been dried at 280°C for 60 minutes. Dissolve it in grade tertiary water and dilute it to a 100ml volumetric flask. Then accurately transfer 10ml to a 250ml beaker and dilute it to 50ml with water. Add 10 drops of bromocresol green-methyl red mixed indicator, and titrate with the prepared hydrochloric acid solution until the solution changes from green to dark red. Boil for 2 minutes, cool, and continue to titrate until the solution turns dark red again. Two people calibrate in parallel, each person calibrates 4 times, and the final value of the concentration cannot exceed 5. Perform a blank test at the same time. The calculation formula is:

[0090]

[0091] in:

[0092] m1 is the mass of sodium carbonate standard, in g;

[0093] V1 is the amount of hydrochloric acid solution, in ml;

[0094] V2 is the amount of hydrochloric acid consumed by the blank, in ml;

[0095] M is the molar mass of 1 / 2Na2CO3 as the basic unit, M = 52.99 g / mol.

[0096] Example 2

[0097] Take high-grade pure ammonium chloride as the sample, determine the nitrogen content according to the analytical procedure, and calculate the recovery rate. It includes the following steps:

[0098] (1) First, weigh 0.4461 g of ammonium chloride and dissolve it in a 100 ml volumetric flask. Pipette 1.00 ml and add it to the reaction device. Add 2 ml of grade 3 water to the reaction device and shake the reaction device to wet the sample evenly. Add 1 ml of potassium permanganate solution to the reaction device and shake the reaction device again. Perform two blanks during the experiment. Then slowly add 10 drops of V to the reaction device using a dropper. H2SO4 :V H2O =1:1 sulfuric acid solution, keep rotating the reaction device, then leave it for 5 minutes, wait for the color of potassium permanganate to fade, and then add potassium permanganate until the purple color no longer fades;

[0099] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O=1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when sulfuric acid is added and no gas is generated.

[0100] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0101] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0102] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0103] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0104] (7) Calculate the total nitrogen content in copper concentrate.

[0105]

[0106] in:

[0107] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0108] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0109] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0110] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0111] m is the mass of the sample, in g.

[0112] The nitrogen content in ammonium chloride measured according to the analytical procedure is shown in Table 1.

[0113] Table 1 Recovery of nitrogen content in ammonium chloride

[0114]

[0115] Example 3

[0116] Take high-grade pure potassium nitrate as sample, determine the nitrogen content according to the analytical procedure, and calculate the recovery rate. It includes the following steps:

[0117] (1) First weigh 0.7942g of potassium nitrate and dissolve it in a 100ml volumetric flask. Pipette 1.00ml and add it to the reaction device. Add 2ml of grade 3 water to the reaction device and shake the reaction device to wet the sample evenly. Add 1ml of potassium permanganate solution to the reaction device and shake the reaction device again. Perform two blanks during the experiment. Then slowly add 10 drops of V to the reaction device with a dropper. H2SO4 :V H2O =1:1 sulfuric acid solution, keep rotating the reaction device, then leave it for 5 minutes, wait for the color of potassium permanganate to fade, and then add potassium permanganate until the purple color no longer fades;

[0118] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O =1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when sulfuric acid is added and no gas is generated.

[0119] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0120] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0121] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0122] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0123] (7) Calculate the total nitrogen content in copper concentrate.

[0124]

[0125] in:

[0126] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0127] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0128] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0129] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0130] m is the mass of the sample, in g.

[0131] The nitrogen content in potassium nitrate measured according to the analytical procedure is shown in Table 2.

[0132] Table 2 Recovery of nitrogen content in potassium nitrate

[0133]

[0134] Example 4

[0135] Take a mixture of ammonium chloride and potassium nitrate as a sample, determine the nitrogen content according to the analytical procedure, and calculate the recovery rate. The following steps are included:

[0136] (1) First weigh 0.7942g of potassium nitrate, dissolve it and add it to a 100ml volumetric flask. Then weigh 0.1416g of ammonium chloride and add it to a 100ml volumetric flask. Pipette 1.00ml of each and add it to the reaction device. Add 2ml of grade 3 water to the reaction device and shake the reaction device to wet the sample evenly. Add 1ml of potassium permanganate solution to the reaction device and shake the reaction device again. Make two blanks along with the experiment. Then slowly add 10 drops of V to the reaction device with a dropper. H2SO4 :V H2O =1:1 sulfuric acid solution, keep rotating the reaction device, then leave it for 5 minutes, wait for the color of potassium permanganate to fade, and then add potassium permanganate until the purple color no longer fades;

[0137] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O =1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when sulfuric acid is added and no gas is generated.

[0138] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0139] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0140] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0141] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0142] (7) Calculate the total nitrogen content in copper concentrate.

[0143]

[0144] in:

[0145] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0146] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0147] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0148] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0149] m is the mass of the sample, in g.

[0150] The nitrogen recovery rate measured according to the analytical procedure when the mixture of potassium nitrate and potassium chlorate was used as the sample is shown in Table 3.

[0151] Table 3 Nitrogen recovery rate when potassium nitrate and ammonium chloride are samples

[0152]

[0153] Example 5

[0154] A copper concentrate sample from Dalian Lanju was selected, and ammonium chloride and potassium nitrate standards were added respectively, and the spike recovery rate of nitrogen was calculated, including the following steps.

[0155] (1) First, weigh three portions of Dalian Lanju's copper concentrate sample and add them to the reaction device, one portion without adding standard, one portion with 1ml of ammonium chloride solution, and the other portion with 1ml of potassium nitrate solution. Add 2ml of grade 3 water to the reaction device, shake the reaction device to evenly wet the sample, add 1ml of potassium permanganate solution to the reaction device, shake the reaction device again, and make two blanks along with the experiment; then use a dropper to slowly add 10 drops of 1:1 sulfuric acid to the reaction device, keep turning the reaction device, and then let it stand for 5 minutes. When the color of potassium permanganate fades, add more potassium permanganate until the purple color no longer fades;

[0156] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O =1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when no gas is generated after adding sulfuric acid.

[0157] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0158] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0159] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0160] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0161] (7) Calculate the total nitrogen content in copper concentrate.

[0162]

[0163] in:

[0164] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0165] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0166] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0167] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0168] m is the mass of the sample, in g.

[0169] The recoveries of nitrogen in samples prepared using potassium nitrate and potassium chlorate as the references, as measured by the analytical procedure, are shown in Table 4.

[0170] Table 4 Recovery rates of samples spiked with potassium nitrate and ammonium chloride as the benchmark

[0171]

[0172] Example 6

[0173] Liaoning Xinhong copper concentrate was selected, and 8 experiments were conducted independently according to the experimental method to calculate the average value and standard deviation, including the following steps:

[0174] (1) First, weigh 8 portions of copper concentrate samples from Liaoning Xinhong and add them to the reaction device. Add 2 ml of grade 3 water to the reaction device, shake the reaction device to evenly wet the sample, add 1 ml of potassium permanganate solution to the reaction device, shake the reaction device again, and make two blanks along with the experiment; then slowly add 10 drops of V to the reaction device with a dropper. H2SO4 :V H2O =1:1 sulfuric acid solution, keep rotating the reaction device, then leave it for 5 minutes, wait for the color of potassium permanganate to fade, and then add potassium permanganate until the purple color no longer fades;

[0175] (2) 0.5 g (±0.01 g) of reduced iron powder was fed into the bottom of the reaction device in step (2) by a special tool, and a small funnel was placed on the bottle mouth. When the violent reaction stopped (about 5 min), the reaction device was placed on a 120° C. electric furnace and slowly heated (the liquid in the reaction device should be kept slightly boiling so as not to cause a large amount of water loss). After the reaction slowed down, 5 drops of V H2SO4 :V H2O =1:1 sulfuric acid solution, until the iron powder is completely reacted; the iron powder reaction is complete when no gas is generated after adding sulfuric acid.

[0176] (3) After step (2) is cooled, add 1.0 g of accelerator and 3 ml of concentrated sulfuric acid to the reaction device through a special tool and shake well. Adjust the temperature of the electric hot plate to 200°C and heat and boil for 30 minutes. Remove and cool, and wait for distillation. The accelerator is a mixture of potassium sulfate: copper sulfate pentahydrate: selenium powder = 100:10:1.

[0177] (4) After step (3) is cooled, wash the small funnel with a small amount of tertiary water, remove the small funnel, transfer all the digestion liquid into a 150ml distillation reaction device, control the liquid volume within 50-60ml, and cool it in cold water. Then slowly add 25ml of 15mol / L sodium hydroxide solution (ensuring that the solution is alkaline), immediately connect the distillation air guide tube, and place it on the hot plate for distillation. The air outlet of the air guide tube is placed in a 100ml small beaker, 50ml of 2% boric acid-indicator mixed solution is added, and it is placed in a tray filled with cold water to absorb the distilled ammonia.

[0178] (5) When the volume of the distillate in step (4) reaches about 30 ml, the distillation is completed. Remove the distillation apparatus and rinse the air pipe with grade 3 water. The volume of the distillate is read from the scale of the small beaker, that is, the volume of the added absorption liquid is 50 ml, and when the total liquid volume reaches 80 ml, the volume of the distillate is 30 ml.

[0179] (6) The absorption liquid turns blue after absorbing ammonia. The distillate from step (5) is titrated with 0.01 mol / L hydrochloric acid standard solution until the color changes from blue to just reddish purple. Record the volume of hydrochloric acid consumed V and the volume of blank hydrochloric acid consumed V0.

[0180] (7) Calculate the total nitrogen content in copper concentrate.

[0181]

[0182] in:

[0183] V is the volume of the acid standard solution used to titrate the test solution, in mL;

[0184] V0 is the volume of the acid standard solution used in the blank titration, in mL;

[0185] C HCL is the concentration of hydrochloric acid standard solution, in mol / L;

[0186] 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL;

[0187] m is the mass of the sample, in g.

[0188] The average values ​​and standard deviations of the analysis results are shown in Table 5 below.

[0189] Table 5 Method precision experiment

[0190]

[0191] It can be seen from the experimental data in Table 5 that the deviation of the total nitrogen content in the copper concentrate measured by the method disclosed in the present invention is very small, the precision of the measurement result is very good, and it fully meets the analysis requirements.

[0192] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for analyzing total nitrogen content in copper concentrate, characterized in that: The following steps are involved: S1, adding a copper concentrate sample with a mass of m and tertiary water to the reaction device to wet the surface of the sample, then adding potassium permanganate solution and mixing evenly to obtain a purple system to be tested; S2, adding sulfuric acid solution to the test system obtained in S1, mixing evenly and letting it stand, waiting for the purple color in the test system to fade away, and then continuing to add potassium permanganate to the test system until the purple color no longer fades; S3, adding reduced iron powder to the bottom of the liquid surface of the test system after the treatment in step S2 to carry out redox reaction, and covering the opening of the reaction device with a lid with holes to prevent splashing, after the violent reaction slows down, heating the reaction device at a temperature of 110-120° C. to keep the test system in a slightly boiling state and continue the redox reaction; after the reaction slows down, adding sulfuric acid solution to the test system to continue the reaction, and repeating this process until the reacted iron powder is completely reacted, and then cooling; S4, adding an accelerator and concentrated sulfuric acid to the test system after treatment in step S3, mixing evenly, heating in an environment of 180-220° C. for 20-40 minutes, and then cooling; S5, remove the cover of the reaction device and rinse with grade tertiary water, and return the rinse water to the system to be tested; transfer the system to be tested into the distillation device and then cool it; S6, adding sodium hydroxide solution to the distillation apparatus described in step S5, adjusting the pH of the system to be tested to alkaline, then starting distillation, and passing the steam obtained by distillation into tertiary water added with a boric acid-indicator mixture through a conduit, and after the distillation is completed, a blue distillate containing dissolved ammonia is obtained; S7, flushing the conduit with tertiary water and returning the flushing water to the distillate; S8, with a concentration of C HCl The distillate obtained in step S7 is titrated with the hydrochloric acid standard solution until the distillate changes from blue to reddish purple, and the consumed volume V of the hydrochloric acid standard solution is recorded; S9, prepare a blank test according to steps S1-S9, except that the copper concentrate sample to be tested is not added to the blank group, the other steps are the same as the test group, and the consumption volume V0 of the hydrochloric acid standard solution of the blank group is recorded; S10, according to the copper concentrate sample m, the concentration of the hydrochloric acid standard solution c HCl , as well as V and V0 to calculate the total nitrogen content in the copper concentrate sample.

2. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The copper concentrate sample to be tested is a copper concentrate sample that has only been reduced and mixed but not dried.

3. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The sulfuric acid solution used in steps S2 and S3 is V H2SO4 :V H2O =1:(0.9-1.1) sulfuric acid solution.

4. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The particle size of the reduced iron powder in step S3 is less than 100 mesh.

5. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The accelerator in step S4 is a mixture of potassium sulfate, copper sulfate pentahydrate and selenium powder.

6. The method for analyzing total nitrogen content in copper concentrate according to claim 5, characterized in that: The mass ratio of potassium sulfate, copper sulfate pentahydrate and selenium powder in the accelerator of step S4 is (90-110):(9-11):

1.

7. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The concentration of the sodium hydroxide solution in step S6 is 500-600 g / L. The preparation method of the sodium hydroxide solution is: 100-120 g of analytical pure sodium hydroxide is slowly added into a container containing 200 ml of water under water cooling, and the mixture is stirred continuously.

8. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The preparation method of the boric acid indicator solution in step S6 is as follows: prepare a solution according to the ratio of pure boric acid: water: methyl orange-methylene blue indicator = 0.02 g: 1 mL: 0.002 mL, then add a sodium hydroxide solution with a concentration of not more than 0.1000 mol / L to the solution to adjust the color of the solution to blue, and then add a standard hydrochloric acid solution to the solution until the solution turns purple-red.

9. The method for analyzing total nitrogen content in copper concentrate according to claim 1, characterized in that: The preparation method of the hydrochloric acid standard solution in step S8 is: use a measuring cylinder to measure 8.3 ml of concentrated hydrochloric acid and pour it into a 10-liter narrow-necked bottle, dilute to 10 L, shake well, and calibrate with a sodium carbonate reference reagent before use.

10. The method for analyzing total nitrogen content in copper concentrate according to claim 9, characterized in that: The method for calibrating the hydrochloric acid standard solution with the sodium carbonate standard reagent is as follows: firstly, accurately weighing a sodium carbonate standard substance with a mass of m1, dissolving it with grade tertiary water and then making up the volume, accurately transferring a certain amount of the sodium carbonate solution to dilute it, and then adding a bromocresol green-methyl red mixed indicator to obtain a green solution; then, titrating the green solution with the prepared hydrochloric acid standard solution until the solution turns dark red, boiling, cooling, and continuing to titrate until the solution turns dark red again, and at the same time, performing a blank test without adding the sodium carbonate standard substance, and calculating the concentration C of the hydrochloric acid standard solution. HCl : in: m1 is the mass of sodium carbonate standard, in g; V1 is the amount of hydrochloric acid standard solution, in ml; V2 is the amount of hydrochloric acid standard solution consumed in the blank test, in ml; M is the molar mass of 1 / 2Na2CO3 as the basic unit, M = 52.99 g / mol.

11. The method for analyzing the total nitrogen content in copper concentrate according to any one of claims 1 to 10, characterized in that: The method for calculating the total nitrogen content in the copper concentrate sample to be tested in step S10 is: in: V is the volume of hydrochloric acid standard solution consumed when titrating the test solution, in mL; V0 is the volume of hydrochloric acid standard solution consumed in the blank titration, in mL; C HCL is the concentration of hydrochloric acid standard solution, in mol / L; 0.014 is the millimolar mass of nitrogen atoms, in g / mmoL; m is the mass of the copper concentrate sample to be tested, in g.

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