Some standard content:
Chemical Industry Standard of the People's Republic of China
HG2557-94
Calcium Magnesium Phosphate
Published on February 9, 1994
Ministry of Chemical Industry of the People's Republic of Chinawww.bzxz.net
Implemented on July 1, 1994
Chemical Industry Standard of the People's Republic of China
Subject Content and Scope of Application
HG2557-94
Replaces ZBG21004-87
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, transportation and storage of calcium magnesium phosphate fertilizer. This standard applies to calcium magnesium phosphate fertilizer made by melting phosphate ore and magnesium and silicon-containing ores at high temperature in a blast furnace or electric furnace, quenching with water, drying and grinding. It is used as a fertilizer and soil conditioner in agriculture. 2
Cited standards
GB/T601
Chemical reagents-Preparation of standard solutions for titration analysis (volumetric analysis) GB/T603
Chemical reagents
GB6003
3 Test sieves
GB/T6678
GB/T6682
Preparation of preparations and products used in test methods General rules for sampling of chemical products
Specifications and test methods for water used in analytical laboratories GB8569
9 Packaging of solid chemical fertilizers
3 Technical requirements
3.1 Appearance: Calcium magnesium phosphate fertilizer is grayish white, grayish green or grayish black powder. Calcium magnesium phosphate fertilizer should meet the requirements of Table 1;
Effective phosphorus pentoxide (P20s) content, %
Moisture, %
Alkalinity (calculated as CaO) content, %
Soluble silicon (SiO2) content, %
Effective magnesium (Mgo) content, %
Fineness: through 250um standard sieve, %
Superior product
Note: If the user does not require the alkali content, soluble silicon and effective magnesium content in the superior product, the manufacturer may not conduct inspection. 4 Test method
Qualified product
In the analysis, unless otherwise specified, analytical pure reagents are used, and the water used should meet the third-grade water specifications in GB/T6682. 4.1 Determination of effective phosphorus pentoxide content
Quinoline phosphomolybdic acid gravimetric method
Approved by the Ministry of Chemical Industry of the People's Republic of China on February 9, 1994 and implemented on July 1, 1994
HG255794
This method is equivalent to the international standard ISO6598-85 "Fertilizer-Determination of phosphorus content-Quinoline phosphomolybdic acid gravimetric method". This method is an arbitration method for determining effective phosphorus pentoxide content. 4.1.1 Scope of application
This method is applicable to the determination of test solutions with phosphorus pentoxide content within the range of 1020 mg. 4.1.2 Summary of the method
Orthophosphate ions in phosphorus-containing solutions react with quinomolybdic acid reagent in an acidic medium to form a yellow quinoline phosphomolybdic acid precipitate, which is filtered, washed, dried and weighed.
4.1.3 Reagents and materials
4.1.3.1 Nitric acid (GB/T626) solution, 1+14.1.3.2 Citric acid (GB/T9855) solution, 20g/L, pH value is about 2.1. Add 0.5g salicylic acid preservative to this solution for easy preservation;
4.1.3.3 Quinoline molybdate reagent
Solution A—Dissolve 70g sodium molybdate in a 400mL beaker containing 100mL water; Solution B—Dissolve 60g citric acid in a 1000mL beaker containing 100mL water, add 85mL nitric acid (GB/T626); Solution C—Add solution A to solution B and mix well; Solution D—Mix 35mL nitric acid and 100mL water in a 400mL beaker, and add 5mL quinoline; Add solution D to solution C, let stand overnight, filter with filter paper or cotton, add 280mL acetone (GB/T686) to the filtrate, and dilute with water to 1000mL. The solution is stored in a polyethylene bottle in a dark place, away from light and heat. 4.1.4 Instruments and equipment
General laboratory glassware and:
4.1.4.1 Glass crucible filter, No. 4, volume 30mL, 4.1.4.2 35-40r/min vertical rotary constant temperature oscillator or other horizontal reciprocating oscillator with equivalent effect; 4.1.4.3 Electric constant temperature drying oven, capable of maintaining a temperature of 180±2℃; 4.1.4.4 Water bath.
4.1.5 Analysis steps
4.1.5.1 Preparation of sample solution
Weigh 1g of sample (accurate to 0.001g), place it in a dry 250mL conical flask or 250mL volumetric flask, accurately add 150mL of citric acid solution (4.1.3.2) preheated to 2830℃, plug the bottle tightly, keep the solution temperature between 28 and 30℃, and place it on the oscillator (4.1.4.2) for 1h. Dry filter and discard the first few milliliters of filtrate, which is the test solution for the determination of phosphorus and magnesium content. 4.1.5.2 Determination
Put a certain amount of test solution (4.1.5.1) (containing 1020 mg of phosphorus pentoxide) into a 500 mL beaker, add 10 mL of nitric acid solution (4.1.3.1), and dilute to 100 mL with water. Preheat to near boiling, add 35 mL of quinoline molybdate reagent, cover with a watch glass, and gently boil on a hot plate for 1 minute or place in a near-boiling water bath to keep warm until precipitation and stratification occur. Take out the beaker and cool to room temperature. Rotate the beaker 3 to 4 times during the cooling process. Filter through a No. 4 glass filter that has been dried to constant weight at 180 ± 2°C in advance. First, filter out the supernatant, then wash the precipitate 1 to 2 times by pouring (about 25 mL of water each time), transfer the precipitate to the filter, and continue washing with water, using a total of about 125 to 150 mL of water. Place the filter with the precipitate in a drying oven at 180 ± 2°C, dry for 45 minutes after the temperature reaches the target, transfer to a desiccator, cool to room temperature, and weigh. 4.1.5.3 Blank test
During the determination, except for not adding the sample, perform the same analytical steps, reagents, and dosages as in 4.1.5.1 and 4.1.5.2 in parallel.
4.1.6 Expression of analysis results
The effective phosphorus pentoxide (P20s) content X1, expressed as mass percentage (%), is calculated according to formula (1): (m1-mz)×0. 03207)
mo×150
Wherein: m1—mass of quinoline phosphomolybdic acid precipitate, HG2557-94
(m1-m2)×481.05
m2—mass of quinoline phosphomolybdic acid precipitate obtained from the blank test, g; mo——mass of sample, gs
V—volume of sample solution, mL
0.03207—coefficient for converting the mass of quinoline phosphomolybdic acid into the mass of phosphorus pentoxide. 4.1.7 Allowable difference
The arithmetic mean of parallel determinations shall be taken as the determination result; the absolute difference of parallel determination results shall not exceed 0.20%; the absolute difference of determination results of different laboratories shall not exceed 0.30%. 4.2 Determination of effective phosphorus pentoxide content Quinoline phosphomolybdic acid volumetric method 4.2.1 Scope of application
The scope of application of this method is the same as that of 4.1.1.
4.2.2 Summary of the method
The yellow precipitate obtained by the quinoline phosphomolybdic acid weight method is washed to remove the adsorbed acid solution, dissolved in an excess of alkali standard solution, and then back-titrated with acid standard titration solution.
4.2.3 Reagents and materials
Same as 4.1.3 Reagents and:
4.2.3.1 Sodium hydroxide (GB/T629) standard solution, c(NaOH) = 0.5 mol/L; prepared, calibrated and compared according to 4.1 of GB/T601. 4.2.3.2 Hydrochloric acid (GB/T622) standard titration solution, c(HCI) = 0.25 mol/L; Measure 22 mL of hydrochloric acid and slowly pour it into a 1000 mL volumetric flask pre-added with about 500 mL of water, cool it, dilute it to the mark with water, and mix it.
Calibrate and compare according to 4.2.2 and 4.2.3 of GB/T601. 4.2.3.3 Carbon dioxide-free water
Prepare according to 4.1.1 of GB/T603.
4.2.3.4 Thymol blue (HG/T3-1223), 1 g/L ethanol solution; Dissolve 0.1 g of thymol blue in 2.2 mL of sodium hydroxide solution with c(NaOH) = 0.1 mol/L, and dilute it to 100 mL with 60% ethanol solution.
4.2.3.5 Phenol (GB/T10729), 1g/L ethanol solution; dissolve 0.1g phenolphthalein in 60mL ethanol (GB/T678), dilute to 100mL. 4.2.3.6 Mixed indicator
Take 3 volumes of thymol blue solution (4.2.3.4) and 2 volumes of phenol solution (4.2.3.5) and mix well. 4.2.4 Instruments and equipment
General laboratory glass instruments and:
4.2.4.1 35-40r/min vertical rotary constant temperature oscillator or other horizontal reciprocating oscillator with equivalent effect;4.2.4.2 Water bath
4.2.5 Analysis steps
Prepare the sample solution according to 4.1.5.1 and the determination according to 4.1.5.2 until ".**. Rotate the beaker 3-4 times during the cooling process". The following operations shall be continued according to the following procedures.
First filter the upper clear liquid with medium-speed filter paper or absorbent cotton, then wash the precipitate 3 to 4 times by pouring method, about 25mL water each time, transfer the precipitate to the filter, continue washing with water until about 20mL of filtrate is obtained, add a drop of mixed indicator and 2 to 3 drops of sodium hydroxide solution 3
HG2557-—94
(4.2.3.1), until the color of the filtrate is similar to the color of the same volume of water treated. Transfer the precipitate together with the filter paper or absorbent cotton to the original beaker, add sodium hydroxide standard solution (4.2.3.1), stir thoroughly until the precipitate dissolves, to about 10mL excess. Add 100mL of carbon dioxide-free water, stir well, add 5 drops of mixed indicator, and titrate with hydrochloric acid standard titration solution (4.2.3.2) until the solution changes from purple to gray-blue to slightly yellow as the end point.
Except that no sample is added, the blank test steps are the same as those in 4.2.5. 4.2.6 Expression of analysis results
The effective phosphorus pentoxide (P20) content X2, expressed as mass percentage (%), is calculated according to formula (2): Xz-
［c,(V1-Vs)-C2(VV))X0.002730X100
mo×150
ci(V,-V)-c(VV))X40.95
Wherein: ci——concentration of sodium hydroxide standard solution, mol/L; C2
concentration of hydrochloric acid standard titration solution, mol/ L; Vi—volume of sodium hydroxide standard solution, mL; V2—volume of hydrochloric acid standard titration solution, mL; V3—volume of sodium hydroxide standard solution for blank test, mL; V—volume of hydrochloric acid standard titration solution for blank test, mL; mo—mass of sample, g;
V—volume of sample solution, mL;
0.002730-
—mass of phosphorus pentoxide expressed in grams equivalent to 1.00mL sodium hydroxide standard solution [c(NaOH)=1.000mol/LJ.
4.2.7 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.20%; the absolute difference of the determination results of different laboratories shall not exceed 0.30%. 4.3 Determination of moisture by gravimetric method
4.3.1 Scope of application
This method is applicable to the sample with a moisture content greater than 0.001g. 4.3.2 Method Summary
In an electric constant temperature drying oven at a certain temperature, the sample is dried within a specified time, and the reduced mass is water. 4.3.3 Instruments and Equipment
4.3.3.1 Electric constant temperature drying oven: can maintain a temperature of 130±2℃4.3.3.2 Weighing bottle with ground mouth cover: diameter 50mm, height 30mm. 4.3.4 Analysis Steps
Weigh 10g of calcium magnesium phosphate fertilizer (accurate to 0.001g), place it in a weighing bottle (4.3.3.2) that has been dried to constant weight at 130±2℃ in advance, and slightly open the lid of the weighing bottle. The weighing bottle should be placed in the drying oven close to the level of the mercury ball of the thermometer. When the temperature reaches 130±2℃, dry it for 20 minutes, take it out, cover the weighing bottle, and weigh it after cooling in a dryer. 4.3.5 Expression of analysis results
Water content (H0) X, expressed as mass percentage (%), is calculated according to formula (3): Xgm1m2×100
-Weighing bottle and sample mass before drying, g; where m1-
(3)
m2——Weighing bottle and sample mass after drying, g;-Sample mass, 8.
4.3.6 Allowable difference
HG2557—94
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.03%; the absolute difference of the determination results of different laboratories shall not exceed 0.06%. 4.4 Determination of alkali content Disodium ethylenediaminetetraacetic acid volumetric method 4.4.1 Scope of application
This method is applicable to the determination of test solutions with alkali content (calculated as CaO) in the range of 25 to 35 mg. 4.4.2 Method Summary
In a solution with a pH value of about 10, triethanolamine is added to mask aluminum, potassium cyanide to mask metal ions such as iron and manganese, ascorbic acid is used to prevent the indicator from being oxidized by iron-cyanide, and chrome black T is used as an indicator. Disodium ethylenediaminetetraacetic acid (EDTA) standard titration solution can be used to quantify calcium and magnesium at the same time. The total amount of the two is expressed as alkaline (calculated as CaO). Citric acid can be added to eliminate interference with silicon, phosphorus, etc. 4.4.3 Reagents and Materials
4.4.3.1 Ascorbic Acid
4.4.3.2 Hydrochloric Acid (GB/T622) Solution, c(HCI)=0.5mol/L Prepare according to 4.2.1 of GB/T601.
4.4.3.3 Citric acid (GB/T9855) solution, 20g/L; 4.4.3.4 Ammonia (GB/T631) solution, 1+4; Triethanolamine solution, 1+3;
4.4.3.6 Potassium cyanide solution, 100g/L, stored in a plastic bottle; 4.4.3.7 Ammonia-ammonium chloride (GB/T658) buffer solution, pH~10, prepared according to 4.4.8 of GB/T603.
4.4.3.8 Disodium ethylenediaminetetraacetic acid (GB/T1401) standard titration solution, c(EDTA)=0.02mol/L, prepared and calibrated according to 4.15 of GB/T601. 4.4.3.9 Methyl red (HG/T3-958) indicator, 1 g/L; prepared according to 4.5.6 of GB/T603.
4.4.3.10 Eriochrome black T indicator, 5 g/L;
0.5 g Eriochrome black T and 4.5 g hydroxylamine chloride (GB/T6685) are dissolved in 95% ethanol (GB/T679), diluted to 100 mL, and stored in a brown bottle.
4.4.4 Analysis steps
4.4.4.1 Preparation of sample solution
Weigh 1g of sample (accurate to 0.001g), place in a 300mL beaker, add 100mL hydrochloric acid solution (4.4.3.2), stir to prevent the sample from condensing, cover with surface III, boil on a hot plate for 5min to dissolve, cool and transfer to a 250mL volumetric flask, add water to the mark and mix. Dry filter and discard the first few milliliters of filtrate. 4.4.4.2 Determination
Pull a certain amount (the total amount of CaO+MgO is 25~35mg) of filtrate (4.4.4.1) into a 250mL conical flask and dilute with water to 100mL. Add 5mL of citric acid solution and a drop of methyl red indicator, and neutralize with ammonia solution (4.4.3.4) until the solution turns yellow (pH~6). Add 0.1g ascorbic acid, 10mL triethanolamine solution and 5mL potassium cyanide solution, and then use a burette to pre-add 90% of the required volume of EDTA standard titration solution (4.4.3.8), 10mL ammonia-ammonium chloride buffer solution and 5 drops of chrome black T indicator, and continue to titrate with EDTA standard titration solution until the red color disappears and completely turns into pure blue. Note: The manufacturer can choose to use potassium cyanide according to the use of phosphate rock in the factory, but when used as an arbitration test, it must be carried out according to the standard. 4.4.5 Expression of analysis results
HG2557-—94
The alkali content (total amount of CaO+MgO, calculated as CaO) X, expressed as mass percentage (%), is calculated according to formula (4): X4 = -VX0. 056 08×100
mo×250
0·V1X1402
mo·V2
Wherein: V1——volume of EDTA standard titration solution used for titration, mL; V2——volume of sample solution absorbed, mL;
-concentration of EDTA standard titration solution, mol/L; -mass of sample, g;
the mass of calcium oxide in grams equivalent to 1.00mL EDTA standard titration solution (Cc(EDTA)=1.000mol/L).
4.4.6 Allowable Difference
The arithmetic mean of the parallel determination results shall be taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.25%; the absolute difference of the determination results of different laboratories shall not exceed 0.30%. 4.4.7 Treatment of cyanide-containing waste liquid
Potassium cyanide is a highly toxic substance. The waste liquid cannot be discharged directly. The cyanide should be decomposed before discharge. When decomposing, add sodium hydroxide solution to the waste liquid. When the pH value reaches about 10, add about 30g of bleaching powder (containing more than 60% effective chlorine) or about 100mL of sodium hypochlorite solution (effective chlorine is 10-13%) to 1L of waste liquid. After standing for 1 hour, discharge it with a large amount of water. 4.5 Determination of soluble silicon content Potassium fluorosilicate volumetric method 4.5.1 Scope of application
This method is suitable for determining test solutions with a silicon dioxide content in the range of 30-50mg. 4.5.2 Summary of the method
In an acidic solution, soluble silicon reacts with potassium fluoride to form potassium fluorosilicate precipitate. The precipitate is hydrolyzed in boiling water to release hydrogen fluoride, which is titrated with a sodium hydroxide standard solution. The generated orthosilicic acid has a very low degree of dissociation and does not participate in the titration in the form of acid. 4.5.3 Reagents and materials
4.5.3.1 Potassium chloride (GB/T646);
4.5.3.2 Nitric acid (GB/T626);
4.5.3.3 Hydrogen peroxide (GB/T6684);
4.5.3.4 Hydrochloric acid (GB/T622) solution, c(HCI)=0.5mol/L; prepared according to 4.2.1 of GB/T601.
4.5.3.5 Potassium fluoride (GB/T1271) solution, 58g/L; dissolve 94g potassium fluoride (KF·2H,0) in 1000mL water in a polyethylene bottle. 4.5.3.6 Potassium chloride ethanol solution, 50g/L Dissolve 50g potassium chloride in 500mL water, dilute to 1000mL with 95% ethanol (GB/T679). 4.5.3.7 Sodium hydroxide (GB/T631) standard titration solution, c(NaOH)=0.1mol/L; prepare, calibrate and compare according to 4.1 of GB/T601. 4.5.3.8 Bromothymol blue-phenol red mixed indicator; dissolve 0.08g bromothymol blue (HG/T3-1222) and 0.1g phenol red (HG/T3-959) in 20mL 95% ethanol, add 50mL water, adjust to pH 7.5 with sodium hydroxide solution (4.5.3.7), and dilute to 100mL with water. 4.5.4 Instruments and equipment
General laboratory instruments and equipment:
HG2557-94
4.5.4.1 35-40r/min vertical rotary constant temperature oscillator or other horizontal reciprocating oscillator with equivalent effect; 4.5.4.2 Polyethylene beaker, 250mL;
4.5.4.3 Polyethylene funnel;
4.5.4.4 Polyethylene stirring rod;
4.5.4.5 Quick filter paper.
4.5.5 Analysis steps
4.5.5.1 Preparation of sample solution
Weigh 1g of sample (accurate to 0.001g), place it in a 250mL dry conical flask or volumetric flask, accurately add 150mL of hydrochloric acid solution (4.5.3.4) preheated to 28-30℃, plug the bottle tightly, keep the solution temperature between 28-30℃, place it on an oscillator (4.5.4.1) and oscillate for 30min, immediately filter it with a dry funnel and filter paper, and discard the first few milliliters of filtrate. 4.5.5.2 Determination
Put a certain amount of test solution (4.5.5.1) (containing 30-50mg silicon dioxide) in a polyethylene beaker, add water to 40mL, add 2g potassium chloride and 10mL nitric acid, stir with a polyethylene rod until most of the potassium chloride is dissolved, add 2mL hydrogen peroxide, and stir until all the potassium chloride is dissolved. Add 8mL potassium fluoride solution (4.5.3.5) while stirring, and place at below 15℃ for 10min. Filter with fast filter paper on a polyethylene funnel, and wash the beaker and filter paper three times with potassium chloride ethanol solution (4.5.3.6). Transfer the precipitate and the filter paper to the original beaker, add 8mL 95% ethanol to rinse the beaker wall, and then add 1mL mixed indicator (4.5.3.8). While crushing the filter paper with a polyethylene rod, titrate with sodium hydroxide standard titration solution (4.5.3.7) until the yellow color fades to a stable blue-purple color (the beaker wall needs to be repeatedly wiped with the broken filter paper), and do not record the reading. Put 150mL boiling water in the beaker, put it in a boiling water bath for hydrolysis, and immediately titrate with sodium hydroxide standard titration solution again until the yellow color fades to a light purple color. Record the volume V1 of the standard sodium hydroxide titration solution. 4.5.5.3 Blank test
During the determination, perform the same analytical steps, reagents and amounts as in 4.5.5.1 and 4.5.5.2 except that no sample is added.
4.5.6 Expression of analysis results
The soluble silicon dioxide (SiO2) content X6, expressed as mass percentage (%), is calculated according to formula (5): (V--V.)cX0. 015 02×100
mo×150
_(Vi-V) ·cX225. 3..
Wherein: Vi——volume of standard sodium hydroxide titration solution, mL; V2——volume of standard sodium hydroxide solution for blank test, mL; V—volume of sample solution, mL;
c—concentration of standard sodium hydroxide titration solution, mol/, mo——mass of sample, g;
.(5)
0.01502——mass of silicon dioxide in grams equivalent to 1.00mL standard sodium hydroxide titration solution [c(NaOH)=1.000mol/L].
4.5.7 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.20%, and the absolute difference of the determination results of different laboratories shall not exceed 0.35%. 4.6 Determination of effective magnesium content
Disodium ethylenediaminetetraacetic acid volumetric method
4.6.1 Scope of application
This method is applicable to the determination of test solutions with magnesium oxide content in the range of 15 to 25 mg. 7
4.6.2 Method Summary
HG2557-94
In a solution containing citric acid, ethylene glycol-bis(α-aminoethyl ether)-tetraacetic acid (EGTA) is used to coordinate calcium ions. In a strong alkaline solution with pH>12, triethanolamine is used to mask iron, aluminum and manganese, and the resulting magnesium hydroxide is precipitated and separated. After the precipitate is dissolved, magnesium is quantified in a solution with pH~10 using chrome black T as an indicator and disodium ethylenediaminetetraacetic acid (EDTA) standard titration solution. 4.6.3 Reagents and materials
4.6.3.1 Ascorbic acid;
4.6.3.2 Ethylene glycol-bis(α-aminoethyl ether)-tetraacetic acid (EGTA) solution, 70 g/L; Weigh 70 g EGTA and dissolve it in 300 mL water, add 200 gL sodium hydroxide solution dropwise until it is completely dissolved, dilute with water to 1000 mL, and mix well.
4.6.3.3 Triethanolamine solution, 1+3;
4.6.3.4 Sodium hydroxide (GB/T629) solution, 200g/L and 20g/L; 4.6.3.5 Hydrochloric acid (GB/T622) solution, 1+9; 4.6.3.6 Ammonia (GB/T631) solution, 1+4; 4.6.3.7 Ammonia-ammonium chloride (GB/T658) buffer solution, pH~10; prepared according to 4.4.8 of GB/T603.
4.6.3.8 Disodium ethylenediaminetetraacetic acid (GB/T1401) standard titration solution, c(EDTA)=0.02mol/L; prepared and calibrated according to 4.15 of GB/T601. 4.6.3.9 Methyl red (HG/T3-958) indicator, 1 g/L; prepared according to 4.5.6 of GB/T603.
4.6.3.10 Malachite green indicator, 1 g/water solution; 4.6.3.11 Eriochrome black T indicator, 5 g/L,
Prepared as in 4.4.3.10.
4.6.3.12 Rapid filter paper.
4.6.4 Analysis steps
4.6.4.1 Preparation of sample solution
Prepare the sample solution according to 4.1.5.1.
4.6.4.2 Determination
Put a certain amount of test solution (containing 15-25 mg magnesium oxide) (4.1.5.1) in a 300 mL beaker, add 5 mL EGTA solution (4.6.3.2), dilute to 100 mL with water. Add 30 mL triethanolamine solution, stir and mix, add 2 drops of malachite green indicator, neutralize with 200 g/L sodium hydroxide solution until the solution is colorless, add 3 mL in excess, heat to about 80 ° C, the precipitate will condense into blocks, filter with fast filter paper, wash the beaker and precipitate with 20 g/L hot sodium hydroxide solution 3 times each, and then use about 20 mL hot hydrochloric acid solution (4.6.3.5) Dissolve the precipitate in the original beaker several times, then wash the filter paper with hot water 6 to 8 times and dilute to 150 mL. Add a drop of methyl red indicator to the beaker, neutralize with ammonia solution (4.6.3.6) until the solution turns yellow (pH ~ 6), add 0.1 g ascorbic acid, 5 mL triethanolamine, 10 mL ammonia-ammonium chloride buffer solution and 5 drops of chrome black T indicator, and titrate with EDTA standard titration solution (4.6.3.8) until the red color disappears and completely turns into pure blue. 4.6.5 Expression of analytical results
Effective magnesium (MgO) content X6, expressed as mass percentage (%), calculated according to formula (6): X = 9-Vi×0.040 31×100
mo×150
C·V1X604.65
mo·V2
Wherein: C——concentration of EDTA standard titration solution, mol/L8
（6）
HG2557-—94
V1——volume of EDTA standard titration solution, mL; V—volume of sample solution, mL;
mo—mass of sample, g;
—the mass of magnesium oxide expressed in grams equivalent to 1.00mLEDTA standard titration solution [c(EDTA)=1.000mol/L].
4.6.6 Allowable difference
The average value of the parallel determination results shall be taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.25%; the absolute difference of the determination results of different laboratories shall not exceed 0.30%. 4.7 Determination of fineness Sieving method
4.7.1 Summary of method
The mass percentage of the sample passing through the specified sieve hole shall be calculated by the sieving method. 4.7.2 Instruments and equipment
4.7.2.1 Standard sieve: pore size 250um, should meet the requirements of R40/3 series in GB6003, with sieve cover and chassis; 4.7.2.2 Balance: sensitivity 0.5g;
4.7.2.3 Electric vibrating sieve machine
4.7.3 Analysis steps
Put the standard sieve with pore size 250um on the chassis, weigh about 100g of sample (accurate to 0.5g), put it in the sieve, cover the sieve cover, clamp it on the vibrating sieve machine (4.7.2.3), vibrate for 10 minutes, then brush the residue on the sieve carefully on the watch glass with a brush and weigh it. Note: If there is no vibrating sieve machine, the sieving operation can be performed manually, but the vibrating sieve machine must be used for arbitration. 4.7.4 Expression of analysis results
The fineness X7 passing through the 250um standard sieve is expressed as a mass percentage (%) and calculated according to formula (7): X,=\omx100.
Where: m——mass of the sample remaining on the sieve, g; mo——mass of the sample,.
5 Inspection rules
5.1 Calcium magnesium phosphate fertilizer shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard. Each batch of products leaving the factory shall be accompanied by a quality certificate in a certain format, including: manufacturer name, factory address, product name, product grade, batch number, production date, product net weight and this standard number. 5.2 The user has the right to conduct quality inspection on the calcium magnesium phosphate fertilizer received in accordance with the provisions of this standard to verify whether its indicators meet the requirements of this standard.
5.3 Calcium magnesium phosphate fertilizer shall be inspected in batches, and the weight of each batch shall not exceed 300t. The user shall regard the products with uniform quality and the same quality certificate as one batch.
5.4 Sampling shall be carried out in the following manner
5.4.1 The number of sampling bags for bagged calcium magnesium phosphate shall be selected in accordance with the provisions of GB/T6678 (Table 2): 9
Total number of packaging bags
82~101
102~125
126~151
152~181
Number of sampling bags
Total number of bags
HG2557-94
Total number of packaging bags
182~216
217~254
255~296
297~343
344~394
395~450
451~512
Number of sampling bags
When the number of bags exceeds 500, the number of sampling bags shall be calculated according to the provisions of 3×n (n is the total number of packaging bags for each batch of products). When sampling, use the sampling needle to obliquely insert from one side of the bag mouth to 3/4 of the depth of the opposite bag to take a uniform sample, and the total amount of the sample shall not be less than 2kg.
Calcium magnesium phosphate fertilizer can also be uniformly sampled at certain time intervals on the packaging belt conveyor, and the sample taken for each batch shall not be less than 5kg.
5.5 Combine the samples, mix carefully, and use the quartering method to reduce them to about 0.5kg (no re-sampling is allowed). Pack them in two clean, dry wide-mouth bottles, polyethylene bottles or plastic bags with ground stoppers. The labels on the bottles (bags) indicate: manufacturer name, product name, batch number, sampling date and name of the sampler. One copy is for inspection, and the other is used as a reserved sample for two months for inspection. 5.6 This standard uses the "rounded value comparison method" specified in GB1250 to determine whether the inspection results meet the requirements of the standard. 5.7 If one of the indicators in the inspection results does not meet the requirements of this standard, re-samples should be taken from twice the amount of packaging bags for re-inspection. If the samples are taken on the belt conveyor, they should be re-sampled according to the provisions of 5.4.1 on sampling in bags and then re-inspected. If the re-inspection results show that only one indicator does not meet the requirements of this standard, the entire batch of calcium magnesium phosphate fertilizer is unqualified. 5.8 When the supply and demand parties have disputes over product quality and need arbitration, the arbitration shall be conducted in accordance with the relevant provisions of the Product Quality Law of the People's Republic of China. During arbitration, the provisions of this standard shall be followed. 6 Packaging, marking, transportation and storage
6.1 Calcium magnesium phosphate fertilizer shall be packaged in composite bags (plastic woven cloth/film/kraft paper three-in-one bag or plastic woven cloth/kraft paper two-in-one bag) or multi-layer bags (plastic woven bag as outer bag, high-density (or modified) polyethylene film bag as inner bag). The technical requirements and packaging materials of the packaging shall comply with the relevant provisions of GB8569.
6.2 The net weight of each bag is 25±0.5kg, 40±0.8kg or 50±1.0kg, and the average net weight of each batch of product bags reaches 25kg, 40kg or 50kg. 6.3 The packaging bag of calcium magnesium phosphate fertilizer shall be marked with the manufacturer's name, address, product name, production date or production batch number, trademark, grade, net weight and this standard number.
6.4 Calcium magnesium phosphate fertilizer can be transported by vehicles, trains, ships and other means of transportation. During transportation, it should be protected from moisture and damage to the packaging bags. 6.5 Calcium magnesium phosphate fertilizer should be stored in a warehouse with a flat, cool, ventilated and dry site. The stacking height of the packages should not exceed 7m. Additional remarks:
This standard was proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhong Fengyuan and Yang Xiaoxia. 101 Standard sieve: pore size 250um, should meet the requirements of R40/3 series in GB6003, with sieve cover and chassis; 4.7.2.2 Balance: sensitivity 0.5g;
4.7.2.3 Electric vibrating sieve machine
4.7.3 Analysis steps
Put the standard sieve with pore size 250um on the chassis, weigh about 100g of sample (accurate to 0.5g), put it in the sieve, cover the sieve cover, clamp it on the vibrating sieve machine (4.7.2.3), vibrate for 10 minutes, then brush the residue on the sieve carefully on the watch glass with a brush and weigh it. Note: If there is no vibrating sieve machine, the screening operation can be performed manually, but the vibrating sieve machine must be used for arbitration. 4.7.4 Expression of analysis results
The fineness X7 passing through the 250um standard sieve is expressed as a mass percentage (%) and calculated according to formula (7): X,=\omx100.
Where: m——mass of the sample remaining on the sieve, g; mo——mass of the sample,.
5 Inspection rules
5.1 Calcium magnesium phosphate fertilizer shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard. Each batch of products leaving the factory shall be accompanied by a quality certificate in a certain format, including: manufacturer name, factory address, product name, product grade, batch number, production date, product net weight and this standard number. 5.2 The user has the right to conduct quality inspection on the calcium magnesium phosphate fertilizer received in accordance with the provisions of this standard to verify whether its indicators meet the requirements of this standard.
5.3 Calcium magnesium phosphate fertilizer shall be inspected in batches, and the weight of each batch shall not exceed 300t. The user shall regard the products with uniform quality and the same quality certificate as one batch.
5.4 Sampling shall be carried out in the following manner
5.4.1 The number of sampling bags for bagged calcium magnesium phosphate shall be selected in accordance with the provisions of GB/T6678 (Table 2): 9
Total number of packaging bags
82~101
102~125
126~151
152~181
Number of sampling bags
Total number of bags
HG2557-94
Total number of packaging bags
182~216
217~254
255~296
297~343
344~394
395~450
451~512
Number of sampling bags
When the number of bags exceeds 500, the number of sampling bags shall be calculated according to the provisions of 3×n (n is the total number of packaging bags for each batch of products). When sampling, use the sampling needle to obliquely insert from one side of the bag mouth to 3/4 of the depth of the opposite bag to take a uniform sample, and the total amount of the sample shall not be less than 2kg.
Calcium magnesium phosphate fertilizer can also be uniformly sampled at certain time intervals on the packaging belt conveyor, and the sample taken for each batch shall not be less than 5kg.
5.5 Combine the samples, mix carefully, and use the quartering method to reduce them to about 0.5kg (no re-sampling is allowed). Pack them in two clean, dry wide-mouth bottles, polyethylene bottles or plastic bags with ground stoppers. The labels on the bottles (bags) indicate: manufacturer name, product name, batch number, sampling date and name of the sampler. One copy is for inspection, and the other is used as a reserved sample for two months for inspection. 5.6 This standard uses the "rounded value comparison method" specified in GB1250 to determine whether the inspection results meet the requirements of the standard. 5.7 If one of the indicators in the inspection results does not meet the requirements of this standard, re-samples should be taken from twice the amount of packaging bags for re-inspection. If the samples are taken on the belt conveyor, they should be re-sampled according to the provisions of 5.4.1 on sampling in bags and then re-inspected. If the re-inspection results show that only one indicator does not meet the requirements of this standard, the entire batch of calcium magnesium phosphate fertilizer is unqualified. 5.8 When the supply and demand parties have disputes over product quality and need arbitration, the arbitration shall be conducted in accordance with the relevant provisions of the Product Quality Law of the People's Republic of China. During arbitration, the provisions of this standard shall be followed. 6 Packaging, marking, transportation and storage
6.1 Calcium magnesium phosphate fertilizer shall be packaged in composite bags (plastic woven cloth/film/kraft paper three-in-one bag or plastic woven cloth/kraft paper two-in-one bag) or multi-layer bags (plastic woven bag as outer bag, high-density (or modified) polyethylene film bag as inner bag). The technical requirements and packaging materials of the packaging shall comply with the relevant provisions of GB8569.
6.2 The net weight of each bag is 25±0.5kg, 40±0.8kg or 50±1.0kg, and the average net weight of each batch of product bags reaches 25kg, 40kg or 50kg. 6.3 The packaging bag of calcium magnesium phosphate fertilizer shall be marked with the manufacturer's name, address, product name, production date or production batch number, trademark, grade, net weight and this standard number.
6.4 Calcium magnesium phosphate fertilizer can be transported by vehicles, trains, ships and other means of transportation. During transportation, it should be protected from moisture and damage to the packaging bags. 6.5 Calcium magnesium phosphate fertilizer should be stored in a warehouse with a flat, cool, ventilated and dry site. The stacking height of the packages should not exceed 7m. Additional remarks:
This standard was proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhong Fengyuan and Yang Xiaoxia. 101 Standard sieve: pore size 250um, should meet the requirements of R40/3 series in GB6003, with sieve cover and chassis; 4.7.2.2 Balance: sensitivity 0.5g;
4.7.2.3 Electric vibrating sieve machine
4.7.3 Analysis steps
Put the standard sieve with pore size 250um on the chassis, weigh about 100g of sample (accurate to 0.5g), put it in the sieve, cover the sieve cover, clamp it on the vibrating sieve machine (4.7.2.3), vibrate for 10 minutes, then brush the residue on the sieve carefully on the watch glass with a brush and weigh it. Note: If there is no vibrating sieve machine, the screening operation can be performed manually, but the vibrating sieve machine must be used for arbitration. 4.7.4 Expression of analysis results
The fineness X7 passing through the 250um standard sieve is expressed as a mass percentage (%) and calculated according to formula (7): X,=\omx100.
Where: m——mass of the sample remaining on the sieve, g; mo——mass of the sample,.
5 Inspection rules
5.1 Calcium magnesium phosphate fertilizer shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard. Each batch of products leaving the factory shall be accompanied by a quality certificate in a certain format, including: manufacturer name, factory address, product name, product grade, batch number, production date, product net weight and this standard number. 5.2 The user has the right to conduct quality inspection on the calcium magnesium phosphate fertilizer received in accordance with the provisions of this standard to verify whether its indicators meet the requirements of this standard.
5.3 Calcium magnesium phosphate fertilizer shall be inspected in batches, and the weight of each batch shall not exceed 300t. The user shall regard the products with uniform quality and the same quality certificate as one batch.
5.4 Sampling shall be carried out in the following manner
5.4.1 The number of sampling bags for bagged calcium magnesium phosphate shall be selected in accordance with the provisions of GB/T6678 (Table 2): 9
Total number of packaging bags
82~101
102~125
126~151
152~181
Number of sampling bags
Total number of bags
HG2557-94
Total number of packaging bags
182~216
217~254
255~296
297~343
344~394
395~450
451~512
Number of sampling bags
When the number of bags exceeds 500, the number of sampling bags shall be calculated according to the provisions of 3×n (n is the total number of packaging bags for each batch of products). When sampling, use the sampling needle to obliquely insert from one side of the bag mouth to 3/4 of the depth of the opposite bag to take a uniform sample, and the total amount of the sample shall not be less than 2kg.
Calcium magnesium phosphate fertilizer can also be uniformly sampled at certain time intervals on the packaging belt conveyor, and the sample taken for each batch shall not be less than 5kg.
5.5 Combine the samples, mix carefully, and use the quartering method to reduce them to about 0.5kg (no re-sampling is allowed). Pack them in two clean, dry wide-mouth bottles, polyethylene bottles or plastic bags with ground stoppers. The labels on the bottles (bags) indicate: manufacturer name, product name, batch number, sampling date and name of the sampler. One copy is for inspection, and the other is used as a reserved sample for two months for inspection. 5.6 This standard uses the "rounded value comparison method" specified in GB1250 to determine whether the test results meet the standard requirements. 5.7 If one of the indicators in the test results does not meet the requirements of this standard, re-samples should be taken from twice the amount of packaging bags for re-testing. If the samples are taken on the belt conveyor, they should be re-sampled according to the provisions of 5.4.1 on sampling in bags and then re-tested. If the re-test results show that only one indicator does not meet the requirements of this standard, the entire batch of calcium magnesium phosphate fertilizer is unqualified. 5.8 When the supply and demand parties have disputes over product quality and need arbitration, the arbitration shall be conducted in accordance with the relevant provisions of the Product Quality Law of the People's Republic of China. During arbitration, the provisions of this standard shall be followed. 6 Packaging, marking, transportation and storage
6.1 Calcium magnesium phosphate fertilizer shall be packaged in composite bags (plastic woven cloth/film/kraft paper three-in-one bag or plastic woven cloth/kraft paper two-in-one bag) or multi-layer bags (plastic woven bag as outer bag, high-density (or modified) polyethylene film bag as inner bag). The technical requirements and packaging materials of the packaging shall comply with the relevant provisions of GB8569.
6.2 The net weight of each bag is 25±0.5kg, 40±0.8kg or 50±1.0kg, and the average net weight of each batch of product bags reaches 25kg, 40kg or 50kg. 6.3 The packaging bag of calcium magnesium phosphate fertilizer shall be marked with the manufacturer's name, address, product name, production date or production batch number, trademark, grade, net weight and this standard number.
6.4 Calcium magnesium phosphate fertilizer can be transported by vehicles, trains, ships and other means of transportation. During transportation, it should be protected from moisture and damage to the packaging bags. 6.5 Calcium magnesium phosphate fertilizer should be stored in a warehouse with a flat, cool, ventilated and dry site. The stacking height of the packages should not exceed 7m. Additional remarks:
This standard was proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhong Fengyuan and Yang Xiaoxia. 101. Provisions on sampling in bags. Sampling shall be retested. If only one index fails to meet the requirements of this standard, the whole batch of calcium magnesium phosphate fertilizer shall be deemed unqualified. 5.8 When the supply and demand parties have disputes over product quality and need to arbitrate, the arbitration shall be conducted in accordance with the relevant product quality arbitration provisions in the "Product Quality Law of the People's Republic of China". During arbitration, the provisions of this standard shall be followed. 6. Packaging, marking, transportation and purchase and storage
6.1 Calcium magnesium phosphate fertilizer shall be packaged in composite bags (plastic woven cloth/film/kraft paper three-in-one bag or plastic woven cloth/kraft paper two-in-one bag) or multi-layer bags (plastic woven bag for outer bag, high-density (or modified) polyethylene film bag for inner bag). The technical requirements of the packaging and the packaging materials shall comply with the relevant provisions of GB8569.
6.2 The net weight of each bag shall be 25±0.5kg, 40±0.8kg or 50±1.0kg, and the average net weight of each batch of product bags shall reach 25kg, 40kg or 50kg. 6.3 The packaging bag of calcium magnesium phosphate fertilizer should indicate the manufacturer's name, factory address, product name, production date or production batch number, trademark, grade, net weight and this standard number.
6.4 Calcium magnesium phosphate fertilizer can be transported by vehicles, trains, ships and other means of transportation. During transportation, it should be protected from moisture and the packaging bags should be protected from damage. 6.5 Calcium magnesium phosphate fertilizer should be stored in a warehouse with a flat, cool, ventilated and dry site. The stacking height of the packages should not exceed 7m. Additional remarks:
This standard was proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhong Fengyuan and Yang Xiaoxia. 101. Provisions on sampling in bags. Sampling shall be retested. If only one index fails to meet the requirements of this standard, the whole batch of calcium magnesium phosphate fertilizer shall be deemed unqualified. 5.8 When the supply and demand parties have disputes over product quality and need to arbitrate, the arbitration shall be conducted in accordance with the relevant product quality arbitration provisions in the "Product Quality Law of the People's Republic of China". During arbitration, the provisions of this standard shall be followed. 6. Packaging, marking, transportation and purchase and storage
6.1 Calcium magnesium phosphate fertilizer shall be packaged in composite bags (plastic woven cloth/film/kraft paper three-in-one bag or plastic woven cloth/kraft paper two-in-one bag) or multi-layer bags (plastic woven bag for outer bag, high-density (or modified) polyethylene film bag for inner bag). The technical requirements of the packaging and the packaging materials shall comply with the relevant provisions of GB8569.
6.2 The net weight of each bag shall be 25±0.5kg, 40±0.8kg or 50±1.0kg, and the average net weight of each batch of product bags shall reach 25kg, 40kg or 50kg. 6.3 The packaging bag of calcium magnesium phosphate fertilizer should indicate the manufacturer's name, factory address, product name, production date or production batch number, trademark, grade, net weight and this standard number.
6.4 Calcium magnesium phosphate fertilizer can be transported by vehicles, trains, ships and other means of transportation. During transportation, it should be protected from moisture and the packaging bags should be protected from damage. 6.5 Calcium magnesium phosphate fertilizer should be stored in a warehouse with a flat, cool, ventilated and dry site. The stacking height of the packages should not exceed 7m. Additional remarks:
This standard was proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shanghai Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhong Fengyuan and Yang Xiaoxia. 10
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