GB/T 14635-2020 (GB/T14635-2020, GBT 14635-2020, GBT14635-2020) & related versions
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Rare earth metals and their compounds -- Determination of total rare earth content
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Rare earth metals and their compounds -- Determination of total rare earth contents
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Rare earth metals and their compounds. Determination of total rare earth contents. Rare earth oxalate gravimetric method
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GB/T 14635-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.99
H 14
GB 14635-2020
Replacing GB/T 14635-2008
Rare Earth Metals and Their Compounds
- Determination of Total Rare Earth Content
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: OCTOBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Method-1: Oxalate Gravimetric Method ... 7
3 Method-2: EDTA Titration Method ... 14
4 Quality Assurance and Control ... 21
Rare Earth Metals and Their Compounds
- Determination of Total Rare Earth Content
1 Scope
This Standard specifies the determination method of total rare earth content in the rare
earth metals and their compounds.
This Standard is applicable to the determination of the total rare earth content in rare
earth metals and their compounds. This Standard contains two methods: Method-1 is
oxalate gravimetric method, and Method-2 is EDTA titration method. Method-1 is
applicable to the determination of the total rare earth content in single and mixed rare
earth metals and their compounds; the determination range is shown in Table 1; it is
not applicable to the determination of the total rare earth content in single and mixed
rare earth metals and their compounds mainly based on erbium, thulium, ytterbium,
and lutetium or the individual content of thorium and lead is greater than 0.1%. Method-
2 is applicable to the determination of the total rare earth content in the single rare
earth metals and mixed rare earth metals and their compounds mainly based on heavy
rare earth holmium, erbium, thulium, ytterbium, and lutetium; the determination range
is shown in Table 2; it is not applicable to the determination of the total rare earth
content in the single rare earth with relative purity less than 99.5%, as well as in a
single rare earth metal and its compounds with other impurity elements greater than
0.5%; it is also not applicable to the determination of the total rare earth content in
materials with individual content of thorium, scandium, and zinc greater than 0.1%.
Table 1 – Determination Range in Method-1
ammonium chloride and 2mL of ammonia water (2.2.5).
2.2.8 Oxalic acid lotion (2g/L).
2.2.9 Hydrochloric acid lotion: 100mL of water contains 2mL of hydrochloric acid (2.2.3).
2.2.10 Accurate range pH test paper (0.5~5.0).
2.2.11 Cresol red solution (2g/L), 50% ethanol solution.
2.3 Apparatus
2.3.1 Analytical balance, the division is no greater than 0.1mg.
2.3.2 High-temperature furnace, the upper limit of temperature is no less than 1000°C.
2.3.3 Oven.
2.3.4 Crucible (platinum crucible or porcelain crucible).
2.4 Specimen
2.4.1 The oxide layer on the surface shall be removed from the metal specimen and
weigh immediately after sampling.
2.4.2 There are many types of rare earth compounds, and their chemical properties
are different. The basic state of using the different compound specimens to determine
the total rare earth content is different. The basic state of measurement of each
different compound is shown in Table 3. There are usually 3 ways:
a) Determine the total rare earth content by the original sample: directly weigh the
sample.
b) Determine the total rare earth content after drying: the sample is dried in an oven
at 105°C for 1h; cool to room temperature in a desiccator; and weigh immediately.
c) Determine the total rare earth content after burning: the sample is burned in a
muffle furnace at 950°C for 1h; cool to room temperature in a desiccator; and
weigh immediately.
(2.2.3) [dissolve testing materials with high cerium content, use nitric acid (2.2.4) to
dissolve] and 1mL of hydrogen peroxide (2.2.2); heat at low temperature to dissolve
completely; and evaporate to about 1mL. Add 20mL of water and heat to dissolve the
salts until clear. Transfer to a 100mL volumetric flask [if there is insoluble matter, filter,
receive the filtrate in a 100mL volumetric flask; wash the beaker and filter paper for
5~6 times by hydrochloric acid lotion (2.2.9); discard the filter paper]; dilute with water
to scale and mix well. Pipette 50mL of test solution into a 300mL beaker.
2.5.3.1.4 Dissolution of rare earth fluoride testing materials: place the testing materials
(2.5.1) in a 200 mL PTFE beaker; add 10 mL of nitric acid (2.2.4), 1 mL of hydrogen
peroxide (2.2.2), and 3mL of perchloric acid (2.2.1); heated at low temperature to emit
perchloric acid fumes. Slightly cold, wash the vessel wall by water. Add 2mL of
perchloric acid (2.2.1); heat at low temperature to emit perchloric acid fumes; when the
testing materials are completely dissolved (if the dissolution is incomplete, repeat it
again); evaporate to about 1mL. Add 20mL of water and heat to dissolve the salts until
clear. After filtering, the filtrate is received in a 300mL beaker; and the beaker and filter
paper are washed by hydrochloric acid lotion (2.2.9) for 5~6 times; and the filter paper
is discarded.
2.5.3.1.5 Dissolution of mixed rare earth oxide of ion-type rare earth ore: place the
testing materials (2.5.1) in a 200mL beaker; add 5mL of water, 4mL of hydrochloric
acid (2.2.3), 1mL of hydrogen peroxide (2.2.2), and 3mL of perchloric acid (2.2.1) [the
rare earth samples containing high cerium shall be dissolved by adding 10mL of nitric
acid (2.2.4)]; after decomposition, add 3mL of perchloric acid (2.2.1); and heat until the
dissolution is complete. Continue to heat until white smoke of perchloric acid is emitted
and evaporated to about 1mL. Take it off and cool it slightly; add 20 mL of hydrochloric
acid (2.2.3); wash the vessel wall by hot water; add 10 mL of water; and heat to dissolve
the salts until clear. Filter by quantitative slow-speed filter paper. Receive the filtrate in
a 300mL beaker. Wash the beaker and filter paper for 5~6 times by hydrochloric acid
lotion (2.2.9); then wash with hot water for 2 times, and discard the filter paper.
2.5.3.1.6 Dissolution of rare earth chloride, rare earth nitrate, and rare earth carbonate
testing materials: place the testing materials (2.5.1) in a 300 mL beaker; add 20 mL of
water, 20 mL of hydrochloric acid (2.2.3) and 1 mL of hydrogen peroxide (2.2.2); heat
at low temperature to dissolve completely; and evaporate to about 5mL [when
dissolving insoluble samples, use 20mL of nitric acid (2.2.4) and 3mL of perchloric acid
(2.2.1) to dissolve]. Add 50mL of water and heat to dissolve the salts until clear. After
filtering, the filtrate is received in a 200mL volumetric flask; and the beaker and filter
paper are washed for 5~6 times by hydrochloric acid lotion (2.2.9); and the filter paper
is discarded. Dilute the filtrate to the mark by water and mix well. Pipette 10mL of test
solution into a 300mL beaker.
2.5.3.1.7 Dissolution of rare earth sulfide testing materials: place the testing materials
(2.5.1) in a 200 mL beaker; add 20 mL of water, 10 mL of hydrochloric acid (2.2.3);
heat at low temperature, and evaporate to about 5mL. Take it off and cool. Add 5mL of
perchloric acid (2.2.1); heat at low temperature to emit white smoke of perchloric acid;
and evaporate to 1mL~2mL; take it off. After cooling slightly, add 5mL of nitric acid
(2.2.4); heat at low temperature and add hydrogen peroxide (2.2.2) dropwise to
complete dissolution. Take if off and cool, filter by slow-speed filter paper; receive the
filtrate in a 300mL beaker; wash the beaker and filter paper by hydrochloric acid lotion
(2.2.9) for 5~6 times; discard the filter paper.
2.5.3.2 Separation of precipitation
2.5.3.2.1 Dilute the test solution (2.5.3.1) by water to about 100mL; heat it to near
boiling; titrate ammonia water (2.2.5) until precipitation just appears; add 0.1mL of
hydrogen peroxide (2.2.2), 30mL of ammonia water (2.2.5); and boil. Take it off, and
filter by medium-speed quantitative filter paper. Wash the beaker for 2~3 times by
ammonium chloride-ammonia water lotion (2.2.7); precipitate for 6~7 times; and
discard the filtrate.
2.5.3.2.2 Put the precipitate and filter paper in the original beaker; add 10 mL of
hydrochloric acid (2.2.3); mash the filter paper. Add 100mL of water and boil. Add 50mL
of oxalic acid solution (2.2.6) near boiling; adjust the pH to 2.0 by ammonia water
(2.2.5), hydrochloric acid (2.2.3) and accurate range pH test paper (2.2.10); or add 4~6
drops of cresol red solution (2.2.11); adjust by ammonia water (2.2.5) to make the
solution orange-yellow (pH 1.8~2.0). Heat to boil; or keep at 80°C~90°C for 40min;
cool to room temperature; and place for 2h.
2.5.3.2.3 Filter by a slow-speed quantitative filter paper; wash the beaker by oxalic acid
lotion (2.2.8) for 2~3 times; wipe the beaker by a small piece of filter paper; transfer all
the precipitate to the filter paper; and wash the precipitate for 8~10 times. Put the
precipitate together with the filter paper into a crucible burnt to a constant mass at
950°C; and heat at low temperature to ash the precipitate and filter paper.
2.5.3.2.4 Burn the crucible (2.5.3.2.3) in a high temperature furnace at 950°C for 1h.
Place the crucible and the burnt rare earth oxide in a desiccator; cool to room
temperature; and weigh its mass.
2.5.3.2.5 Repeat operation in 2.5.3.2.4 until the mass of the crucible together with the
burnt material is constant.
2.6 Calculation of analysis results
2.6.1 Calculation and expression of the total rare earth content in rare earth metal
testing materials
The total rare earth content is calculated by the mass fraction w (RE) of rare earth
metals (RE); and calculated as per Formula (1):
add 5mL of hydrochloric acid (3.2.5); dilute to the mark by water, and mix well.
3.2.13 Ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution
(c≈0.01mol/L):
a) Preparation: take about 7.5g of ethylenediaminetetraacetic acid disodium salt
(3.2.13) in a 250mL beaker; add a small amount of water to dissolve; transfer the
solution to a 2L volumetric flask; dilute to the mark by water, and mix well.
b) Calibration: pipette 25.00mL of zinc standard solution (3.2.12) in a 250mL
triangular flask; add 50mL of water, 1 drop of methyl orange (3.2.9) or p-
nitrophenol (3.2.10) indicator. Use ammonia water (3.2.6) and hydrochloric acid
(3.2.5) to adjust the solution to just turn yellow; add 5mL of
hexamethylenetetramine buffer solution (3.2.11), 2 drops of xylenol orange
(3.2.8); use the EDTA standard titration solution (3.2.13) to titrate the solution till
it turns from red (when the acidity is adjusted by methyl orange) or purple (when
the acidity is adjusted by p-nitrophenol) just to yellow, which is the end point.
Calibrate 3 portions in parallel; and the range of the volume of the consumed
EDTA standard titration solution (3.2.13) shall not exceed 0.10 mL; take the
average value.
The concentration c of the EDTA standard titration solution is calculated in mol/L, which
is calculated as per Formula (3):
Where:
ρ – mass concentration of zinc standard solution, in g/L;
V5 –volume of the separately-pipetted zinc standard solution, in mL;
V6 – volume of EDTA standard titration solution consumed by titration of zinc, in mL;
M1 – molar mass of the zinc, in g/mol.
3.3 Specimen
3.3.1 The surface oxide layer shall be removed from the metal specimen; and weigh
immediately after sampling.
3.3.2 There are many types of rare earth compounds and their chemical properties are
different. The basic state of the different compound specimen to determine the total
rare earth content is difference. The basic state of measurement for each different
compound is shown in Table 8. There are usually 3 ways:
3.4.3.1.2 Dissolution of rare earth oxide and rare earth hydroxide (except cerium oxide,
terbium oxide and cerium hydroxide): place the testing materials (3.4.1) in a 150mL
beaker; and add 10mL of hydrochloric acid (3.2.5); cover with a watch glass; heat at
low temperature to dissolve completely; take it off and cool to room temperature.
Transfer the solution into a 200mL volumetric flask; dilute to the mark with water, and
mix well.
3.4.3.1.3 Dissolution of cerium oxide, terbium oxide and cerium hydroxide: place the
testing materials (3.4.1) in a 150mL beaker; add 10mL of nitric acid (3.2.4), 1mL of
hydrogen peroxide (3.2.3); cover with a watch glass; heat at low temperature to
dissolve completely and steam until there are no small bubbles (volume is about
1mL~2mL); take if off and cool. Add 2mL of hydrochloric acid (3.2.5); wash the vessel
wall and tableware by water; dissolve the salts at low temperature; take it off and cool
to room temperature. Transfer the solution into a 200mL volumetric flask; dilute to the
mark with water, and mix well.
3.4.3.1.4 Dissolution of rare earth fluoride: place the testing materials (3.4.1) in a
150mL beaker; add 5mL of perchloric acid (3.2.2), 5mL of nitric acid (3.2.4); and heat
at low temperature until it emits the white smoke of perchloric acid. Take it off and cool
slightly; add 2mL of perchloric acid (3.2.2); cover with watch glass; heat at low
temperature to dissolve till it emits the white smoke of perchloric acid (if the dissolution
is incomplete, repeat again); and steam to about 1mL; take it off, and cool. Add 2mL of
hydrochloric acid (3.2.5); wash the vessel wall and watch glass by water; dissolve the
salts at low temperature; take it off and cool to room temperature. Transfer the solution
into a 200 mL volumetric flask; dilute to the mark with water, and mix well.
3.4.3.1.5 Dissolution of rare earth chloride: place the testing materials (3.4.1) in a
200mL beaker; add 20mL of water, 10mL of hydrochloric acid (3.2.5); cover with a
watch glass; and take it off and cool to the room temperature after heating at low
temperature to dissolve completely. Transfer the solution into a 200 mL volumetric flask;
dilute to the mark with water, and mix well.
3.4.3.1.6 Dissolution of rare earth sulfide: place the testing materials (3.4.1) in a 150mL
beaker; add 20mL of water, 10mL of hydrochloric acid (3.2.5); heat to about 5mL at low
temperature; take it off and cool. Add 5mL of perchloric acid (3.2.2); heat at low
temperature to emit white smoke of perchloric acid; and evaporate to 1mL~2mL; and
take it off. After cooling slightly, add 5mL of nitric acid (3.2.4); heat at low temperature
and titrate hydrogen peroxide (3.2.3) until the sample is completely dissolved. Take it
off and cool; wash the vessel wall and watch glass by water; dissolve the salt at low
temperature; and cool to room temperature. Transfer the solution into a 200mL
volumetric flask; dilute to the mark with water, and mix well.
3.4.3.2 Titration
Pipette the test solution (3.4.3.1) into a 250mL triangular flask according to Table 9;
......
GB/T 14635-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.99
H 14
Replacing GB/T 8762.1-1988, GB/T 12687.1-1990,
GB/T 14635.1 ~ 14635.3-1993, GB/T 16484.19-1996, GB/T 18882.1-2002
Rare earth metals and their compounds -
Determination of total rare earth contents
ISSUED ON. JUNE 17, 2008
IMPLEMENTED ON. DECEMBER 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3
Method 1 -- Oxalate gravimetric method ... 6
1 Scope ... 6
2 Method principle ... 6
3 Reagents and materials ... 7
4 Apparatus ... 7
5 Specimen ... 7
6 Analysis steps ... 8
7 Calculation of analysis results ... 10
8 Precision ... 11
Method 2 -- EDTA titration ... 12
9 Scope ... 12
10 Method principle ... 13
11 Reagents ... 13
12 Specimen ... 14
13 Analysis steps ... 15
14 Calculation and expression of analysis results ... 16
15 Precision ... 19
16 Quality assurance and control ... 20
Foreword
This Standard is an integrated revision to GB/T 8762.1-1988 "Yttrium oxide and
europium oxide of phosphor grade - Determination of total rare earth oxide
content - EDTA volumetric method", GB/T 14635.1-1993 "Rare earth metals
and their compounds. Determination of total rare earth contents. Rare earth
oxalate gravimetric method", GB/T 14635.2-1993 "Rare earth metals and their
compounds. Determination of total rare earth contents. EDTA volumetric
method", GB/T 14635.3-1993 "Heavy rare earth metals and their compounds.
Determination of total rare earth contents. EDTA volumetric method", GB/T
16484.19-1996 "Methods for chemical analysis of rare earth chloride and
carbonate - Determination of total rare earth oxide content", GB/T 12687.1-
1990 "Chemical analysis of nitrate of rare earth for agriculture - Determination
of total rare earth oxide content - Gravimetric method", GB/T 18882.1-2002
"Chemical analysis methods for mixed rare earth oxide of ion-absorbed type
RE ore - Determination of total rare earth contents - Oxalate gravimetric
method".
Compared with the above standards that have been integrated for revision, the
main changes in this Standard are as follows.
-- combined GB/T 14635.1-1993, GB/T 16484.19-1996, GB/T 12687.1-1990,
GB/T 18882.1-2002 into Method One;
-- combined GB/T 8762.1-1988, GB/T 14635.2-1993, GB/T 14635.3-1993
into Method Two;
-- in the range for determination in Method One, added individual rare earth
metal and its compounds;
-- in Method One, adjusted the lower determination limit of rare earth
carbonate from 20.0% to 10.0%;
-- in Method One, adjusted the pH2 of acidity of oxalic acid precipitated rare
earth to pH1.8 ~ 2;
-- in Method One, adjusted the burning temperature of rare earth oxide from
1000°C to 950°C;
-- in Method One, modified the way that rare earth carbonate pretreatment is
dried by 105°C TO the way that rare earth carbonate of ionic rare earth
ore is burned at 950°C; other rare earth carbonates are directly weighed
for bulk sample;
-- in Method Two, adjusted the range of determination for rare earth metals
and rare earth oxides from 95.0% ~ 99.5% to 98.0% ~ 99.5%;
Rare earth metals and their compounds -
Determination of total rare earth contents
Method 1 -- Oxalate gravimetric method
1 Scope
This Method specifies the determination method for total rare earth contents in
rare earth metals and their compounds.
This Method is applicable to the determination of total rare earth contents in
individual and mixed rare earth metals and their compounds. See Table 1 for
the range of determination.
This Method is not applicable to the determination of total rare earth contents
in individual and mixed rare earth metals and their compounds of which
holmium, erbium, thulium, ytterbium, lutecium compose the main body or the
thorium content, the lead content (mass fraction) is greater than 0.1%,
respectively.
Table 1
Specimen Range of determination (mass fraction)/%
Rare earth metal 95.0 ~ 99.5
Rare earth oxide 95.0 ~ 99.8
Rare earth hydroxide 55.0 ~ 75.0
Rare earth fluoride 65.0 ~ 80.0
Rare earth chloride 40.0 ~ 60.0
Rare earth carbonate 10.0 ~ 60.0
Rare earth nitrate 30.0 ~ 70.0
Ionic rare earth ore mixed rare earth oxide 80.0 ~ 99.0
2 Method principle
After the specimen is decomposed by acid, precipitate rare earth with ammonia
so as to separate calcium, magnesium, etc. Dissolve rare earth with
hydrochloric acid. Under pH1.8 ~ 2, precipitate rare earth with oxalic acid so as
to separate iron, etc. At 950°C, burn rare earth oxalate into oxide. Weigh its
mass. Calculate the total rare earth contents.
6.3.1.3 Dissolution of rare earth fluoride test material. place the test material
(6.1) into a 200mL beaker. Add 10 mL of nitric acid (3.4), 1 mL of hydrogen
peroxide (3.2) and 3 mL of perchloric acid (3.1). Heat at a low temperature till
perchloric acid smokes. Cool it for a while. Wash the beaker wall with water.
Add 2 mL of perchloric acid (3.1). Heat at a low temperature till perchloric acid
smokes. When the test materials are dissolved completely, evaporate to about
1 mL. Add 20 mL of water. Heat to dissolve the salt till it is clear. Filter. Receive
the filtrate in a 300mL beaker. Wash the beaker and filter with hydrochloric acid
liquid (3.9) 5 ~ 6 times. Discard the filter paper.
6.3.1.4 Dissolution of ionic rare earth ore mixed rare earth oxide, rare earth
carbonate of ionic rare earth ore. place the test material (6.1) into a 300mL
beaker. Add 5 mL of water, 4 mL of hydrochloric acid (3.3), 1 mL of hydrogen
peroxide (3.2), 3 mL of perchloric acid (3.1) [for test material containing high
cerium] as well as 1 mL of hydrogen peroxide (3.2). After separation, add 3 mL
of perchloric acid (3.1). Heat till it dissolves completely. Continue heating till
perchloric acid has white smoke. And evaporate to about 1 mL. Remove. Cool
for a while. Add 20 mL of hydrochloric acid (3.3). Wash the container wall with
hot water. Add 10 mL of water. Heat to dissolve the salt till it is clear. Filter with
quantitative slow filter paper. Receive the filtrate in a 300mL beaker. Wash the
beaker and filter with hydrochloric acid liquid (3.9) 5 ~ 6 times. Wash twice with
hot water. Discard the filter paper.
6.3.1.5 Dissolution of rare earth chloride, rare earth nitrate, rare earth carbonate
(excluding rare earth carbonate of ionic rare earth ore) test materials. place the
test material (6.1) into a 300mL beaker. Add 20 mL of water, 20 mL of
hydrochloric acid (3.3) and 1 mL of hydrogen peroxide (3.2). Heat till it dissolves
completely. Evaporate to about 5 mL [for insoluble test materials, use 20 mL of
nitric acid (3.4) and 2 mL of perchloric acid (3.1) to dissolve]. Add 50 mL of water.
Heat to dissolve the salt till it is clear. Filter. Receive the filtrate in a 200mL
beaker. Wash the beaker and the filter paper with hydrochloric acid liquid (3.9)
5 ~ 6 times. Discard the filter paper. Dilute the filtrate with water to the scale.
Mix evenly. Pipette 10 mL of test solution to a 300mL beaker.
6.3.2 Precipitation separation
6.3.2.1 Dissolute the test solution (6.3.1) with water to about 100 mL. Heat it till
it nearly boils. Add ammonia water (3.5) till precipitate just appears. Add 0.1 mL
of hydrogen peroxide (3.2), 30 mL of ammonia water (3.5). Boil it till it is boiled.
Filter with medium speed quantitative filter paper. Wash the beaker with
ammonium chloride-ammonia liquid (3.7) 2 ~ 3 times. Perform precipitation 6 ~
7 times. Discard the filtrate.
6.3.2.2 Place the precipitate and filter paper in the original beaker. Add 10 mL
of hydrochloric acid (3.3). Crush the filter paper. Add 100 mL of water. Boil it till
it is boiled Add 50 mL of oxalic acid solution (3.6) that is almost boiled. Adjust
pH to 2.0 with ammonia (3.5), hydrochloric acid (3.3) and precision pH test
paper (3.10). Or add 4 ~ 6 drops of cresol red solution (3.11). Adjust with
ammonia (3.5) to make the solution orange (pH 1.8 ~ 2.0). Heat it till it is boiled;
or heat at 80°C ~ 90°C for 40 min. Cool to room temperature. Place for 2h.
6.3.2.3 Filter with slow quantitative filter paper. Wash the beaker with oxalic acid
liquid (3.8) 2 ~ 3 times. Wipe the beaker with a small piece of filter paper.
Transfer all the precipitate to the filter paper. Wash the precipitate 8 ~ 10 times.
Put the precipitate together with the filter paper in the platinum crucible that has
been burnt to constant mass at 950°C. Heat at a low temperature. Perform
ashing for the precipitate and the filter paper.
6.3.2.4 Burn the platinum crucible (6.3.2.3) in a 950°C high-temperature
furnace for 1h. Place the platinum crucible and the finished rare earth oxide into
the dryer. Cool to room temperature. Weigh its mass.
6.3.2.5 Repeat the operation of 6.3.2.4 till it reaches constant weight.
7 Calculation of analysis results
7.1 Calculation and expression of total rare earth contents in rare earth
compound test material
Calculate the total rare earth contents (REO) according to formula (1),
expressed in mass fraction (%).
Where,
m1 - the mass of platinum crucible and burnt material, in grams (g);
m2 - the mass of platinum crucible, in grams (g);
m0 - the mass of test material, in grams (g);
V1 - the volume of divided test solution, in millimeters (mL);
V0 - the volume of original test solution, in millimeters (mL).
7.2 Calculation and expression of total rare earth contents in rare earth
carbonate of ionic rare earth ore test material
Calculate the total rare earth contents (REO) according to formula (2),
expressed in mass fraction (%).
solution (c≈0.02 mol/L).
11.12.1 Preparation. weigh about 15 g of disodium edetate in a 250mL beaker.
Dissolve in small amounts of water. Dissolve with water in a 2L volumetric flask.
Mix evenly.
11.12.2 Calibration. pipette 25.00 mL of zinc standard solution (11.11) into a
250mL flask. Add 50 mL of water, 1 drop of methyl orange indicator (11.9).
Adjust the solution to yellow with ammonia (11.6) and hydrochloric acid (11.4).
Add 5 mL of hexamethylenetetramine buffer solution (11.10), 2 drops of xylenol
orange (11.8). Titrate with EDTA standard titration solution (11.12) until the
solution turns from red to yellow. Perform 3 portions of parallel calibration. The
difference in volume of the EDTA standard titration solution (11.12) consumed
shall not exceed 0.10 mL. Take its average value.
Calculate the actual concentration of the EDTA standard titration solution
according to formula (4).
Where,
c - the actual concentration of EDTA standard titration solution, in molar per
liter (mol/L);
c0 - the concentration of zinc standard solution, in grams per liter (g/L);
V1 - the number of milliliters of divided zinc standard solution, in milliliters
(mL);
V2 - the volume of EDTA standard titration solution consumed by titration of
zinc, in milliliters (mL);
M - the molar mass of zinc, in grams per mole (g/mol).
12 Specimen
12.1 Metal specimen shall be removed from the surface oxide layer. Weigh the
specimen immediately after sampling.
12.2 Burn rare earth oxide at 950°C for 1h. Place it in the dryer. Cool to room
temperature. Weigh immediately.
12.3 For rare earth chloride. crush the specimen. Immediately place it in the
weighing bottle. Weigh immediately.
150mL beaker. Add 5 mL of perchloric acid (11.1), 5 mL of nitric acid (11.3).
Heat it at a low temperature till it is dissolved and it has perchloric acid white
smoke. Cool it for a while. Add 2 mL of perchloric acid (11.1). Cover with a watch
glass. Heat it at a low temperature till it is dissolved and it has perchloric acid
white smoke (if it is not dissolved completely, repeat once). Steam to about 1
mL. Cool. Add 2 mL of hydrochloric acid (11.4). Wash the container wall and
watch glass with water. Dissolve the salt at a low temperature. Transfer the
solution into a 100mL volumetric flask. Dilute with water to scale. Mix evenly.
13.3.1.5 Dissolution of rare earth chloride. place the test material (13.2) in a
300mL beaker. Add 20 mL of water, 10 mL of hydrochloric acid (11.4). Cover
with a watch glass. Heat it at a low temperature till it is dissolved. Cool to room
temperature. Transfer the solution into a 200mL volumetric flask. Dilute with
water to scale. Mix evenly.
13.3.2 Titration
Weigh 10.00 mL of test solution (13.3.1) in a 250mL triangle bottle. Add 50 mL
of water, 0.2 g of ascorbic acid (11.2), 2 mL of sulfosalicylic acid (11.7), 1 drop
of methyl orange (11.9). Adjust the solution to yellow with ammonia (11.6) and
hydrochloric acid (11.4). Add 5 mL of hexamethylenetetramine buffer solution
(11.10), 2 drops of xylenol orange (11.8). Titrate with EDTA standard titration
solution (11.12) until the solution turns from red to yellow.
14 Calculation and expression of analysis results
14.1 Calculation and expression of total rare earth contents in rare earth
compound test material
Calculate the total rare earth contents (REO) according to formula (5), in mass
fraction (%).
Where,
M - the molar mass of rare earth oxides contained in the test material, in
grams per molar (g/mol);
c - the concentration of EDTA standard titration solution, in molars per liter
(mol/L);
V - the volume of EDTA standard titration solution consumed, in milliliters
(mL);
V - the volume of EDTA standard titration solution consumed, in milliliters
(mL);
V1 - the total volume of test solution, in milliliters (mL);
V2 - the volume of divided test solution, in milliliters (mL);
m0 - the mass of test material, in grams (g);
M - 1/x of the molar mass of the mixed oxidized rare earth in which the
relative proportion of rare earth elements is consistent in the test material, in
grams per molar (g/mol); calculated according to formula (8).
Where,
Pi - the mass fraction of each rare earth oxide in the total amount of
corresponding mixed rare earth oxides contained in test material (%);
ki - the molar mass of each rare earth oxide (RExOy), in grams per mole
(g/mol);
x - the number of atoms of rare earth in each rare earth oxide (RExOy)
molecule.
14.4 Calculation and expression of total rare earth contents in mixed rare
earth metal test material of which holmium, erbium, thulium, ytterbium,
lutecium compose the main body
Calculate the total rare earth contents (RE) according to formula (9), in mass
fraction (%).
Where,
c - the concentration of EDTA standard titration solution, in molars per liter
(mol/L);
V - the volume of EDTA standard titration solution consumed, in milliliters
(mL);
V1 - the total volume of test solution, in milliliters (mL);
V2 - the volume of divided test solution, in milliliters (mL);
......
| Standard ID | GB/T 14635-2020 (GB/T14635-2020) | | Description (Translated English) | Rare earth metals and their compounds -- Determination of total rare earth content | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H14 | | Word Count Estimation | 14,168 | | Date of Issue | 2020-11-19 | | Date of Implementation | 2021-10-01 | | Older Standard (superseded by this standard) | GB/T 14635-2008 | | Regulation (derived from) | National Standard Announcement No. 26 of 2020 | | Standard ID | GB/T 14635-2008 (GB/T14635-2008) | | Description (Translated English) | Rare earth metals and their compounds. Determination of total rare earth contents | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H14 | | Classification of International Standard | 77.120.99 | | Word Count Estimation | 13,112 | | Date of Issue | 2008-06-17 | | Date of Implementation | 2008-12-01 | | Older Standard (superseded by this standard) | GB/T 12687.1-1990; GB/T 14635.1-1993; GB/T 14635.2-1993; GB/T 14635.3-1993; GB/T 16484.19-1996; GB/T 18882.1-2002; GB/T 8762.1-1988 | | Drafting Organization | Beijing Nonferrous Metal Research Institute | | Administrative Organization | Rare National Standardization Technical Committee | | Regulation (derived from) | National Standard Approval Announcement 2008 No.10 (Total No.123) | | Proposing organization | National Development and Reform Commission, the Office of Rare Earth | | Issuing agency(ies) | Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China | | Summary | This standard specifies the determination of single and mixed rare earth metals and rare earth compounds in total. This method is applicable to both single and mixed rare earth rare earth determination of total and compounds. Measuring range in Table 1. This method does not apply to holmium, bait, thulium, ytterbium, lutetium as the main or thorium, lead content (mass fraction) for the determination of the major single and mixed total rare earth rare earth metals and their compounds in 0. 1%. | | Standard ID | GB/T 14635.1-1993 (GB/T14635.1-1993) | | Description (Translated English) | Rare earth metals and their compounds. Determination of total rare earth contents. Rare earth oxalate gravimetric method | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H14 | | Classification of International Standard | 77.120.70 | | Word Count Estimation | 4,419 | | Date of Issue | 1993/9/15 | | Date of Implementation | 1994/6/1 | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 10, 2008 (No. 123 overall) | | Proposing organization | China Nonferrous Metals Industry Corporation | | Issuing agency(ies) | State Bureau of Technical Supervision |
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