Measurement method of free silica in the air of workplace, such as dust, limestone, ore, etc.~A good helper for adjustable electric heating plate and silicon carbide electric heating plate
Free silicon dioxide determination ~ a good helper for silicon carbide heating plate and electric heating plate ! !
Determination of Free Silica
D⒔1 Method Summary
Use the properties of pyrophosphoric acid that can dissolve various ores at a temperature of 245 to 250 ℃, but cannot dissolve quartz silica to determine the content of free silica.
D⒔2 Analysis step
Weigh 0.1g sample into a 50mL Erlenmeyer flask, add 15mL pyrophosphoric acid, use a glass rod until all the sample powder is soaked in acid, insert a thermometer into it and place it on a low electric furnace or electric hot plate, and heat To 250℃, in the heating process, stir with a glass rod at all times, and keep the temperature at 245～250℃ for 15min, remove and cool to 100～150℃, move it into the cooling tank and continue to cool to 50～60℃, take it out, and put the inside Pour the dissolved substance dropwise into a 250mL beaker containing 100mL of distilled water, and then wash the Erlenmeyer flask with water. At this time, the volume is 150～200mL, boil it, filter it with dense filter paper while it is hot, and wash it with 0.1mol/L hydrochloric acid for 3～ Times, and then washed with distilled water until there is no chloride ion reaction. Put the filter paper and the precipitate into a porcelain crucible with a known constant amount for ashing, burn and cool for weighing. For accurate measurement, wash with hot water until there is no phosphate ion (usually 20 times or use a solution of ammonium molybdate and ascorbic acid to check). Put the precipitate into a clean platinum crucible with a known constant amount, first ash on an electric furnace, then burn it in a high-temperature furnace at 900～950℃ for 30 minutes, cool, weigh, and then drop sulfuric acid (1+1) into the platinum crucible ), soak all the silica with sulfuric acid, then add 5-10mL of hydrogen acid, put it on the sand bath and heat it until it evaporates and no white smoke is emitted, then burn it in a high-temperature furnace at 900-950℃ for 20 minutes , Cooling and weighing, the secondary weight difference is the mass of free silica.
D⒔3 The mass percentage of free silica is calculated as follows:
m1 ×m2
XSiO2 =——————×100
m
Where: m1—weight of residue and platinum crucible before hydrogen acid treatment, g;
m2— weight of residue and platinum crucible after hydrogen acid treatment, g;
m—mass of sample, g.
D⒔4 Attention:
When preparing pyrophosphoric acid, heat 85% phosphoric acid (secondary product) to boiling and gradually evaporate part of the water to 250°C and no more bubbles. Let it cool for use. Note that the temperature should reach 250°C, not low. At 150°C, it should not be lower than 150°C, because it starts to lose crystal water and transform into pyrophosphate when it is higher than 150°C.
If the sample contains sulfide, you need to add several milligrams of ammonium nitrate crystals when the pyrophosphoric acid solution is heated to dissolve, and heat at 120～170℃. When the ammonium nitrate decomposes, it will oxidize the sulfide and emit a brown gas of nitrogen dioxide at the same time. Keep this temperature for a while, so that the sulfide is completely dissolved and then increase the temperature (note that the temperature should not be too high, otherwise it will cause an explosion).
If the sample contains carbonate, it must be heated from low temperature after adding acid, otherwise the sample will splash out if the effect is too strong, causing inaccurate analysis.
The temperature and time for dissolving pyrophosphoric acid is 15min at 245～250℃. When the temperature exceeds 252°C, a colloidal precipitate will form, and the sample must be redone.
When diluting, the speed should not be too fast or too slow, it should be poured drop by drop.
*Instrument in the experiment:
silicon carbide electric heating plate, adjustable electric heating plate, adjustable electric
heating plate
NanoHeat Silicon Carbide Heating Plate
Silicon Carbide Heating Plate NanoHeat is a world-class thermal energy technology with superb quality and has won the Asian Creative Award successively! The 2009 Hong Kong Awards for Industry Science and Technology Achievement Award, and the 2008 Science and Technology Achievement Certificate of Merit. More than 35 technologies! More than 40 product designs! !
Silicon carbide heating plate-five major-core technical advantages
1. The plate surface adopts high-density silicon carbide material, which is resistant to high acid and alkali and corrosion;
2. Nano thermal energy technology, fast heating, heating rate calculation of 5 degrees per second;
3. Nano-ceramic heating element, super far-infrared heat radiation, strong penetrating power;
4. Large heating area, uniform temperature; no mechanical heating components, no magnetic field interference;
5. Dry burning can be continued for
a long time; 1. HTL Series of laboratory nano silicon carbide heating plates HTL-300EXT HTL-400EXT HTL-500EXT HTL-600EXT
II. Uses:
Laboratory nano silicon carbide heating plates are widely used in precious metals, jewelry, metallurgy, agriculture, soil, environmental protection, food, scientific research institutes Laboratories, laboratories, universities, colleges, etc. It can be used for sample heating, baking, digestion, acid removal , etc.
(1) Performance:
laboratory nano silicon carbide heating plate HTL-300EXT
nano thermal energy technology, no mechanical heating components, dry burning, no electromagnetic field interference and hazards, rapid heating It takes only 1 second to reach 5°C, and only 8 minutes to reach 450, which greatly improves work efficiency;
project equipment name and
model/parameters
Laboratory nano heating plate
HTL-400EXT
workbench size (material)
440*340 (high-density silicon carbide board )
400*300 (heating zone)
set temperature
RT-360℃
temperature
controller split temperature control system, intelligent program segmented PID control
temperature control accuracy
±0.1℃
time setting
1min~999hr
working voltage
AC220V/50Hz
technical parameters: model HTL-400EXT
★ heating fabric: high-density carbonization Silicon plate
★Heating method: Nano thermal energy technology (no mechanical heating components)
★Power requirement: 220-240V AC, 50/60 Hz
★Output power:
3000W ★Product size: 440 (length) x340 (width) x 70 (height) ) Mm
★ Heating zone: 400 (length) x 300 (width) mm
★ Temperature control range: room temperature-360 ℃
★ Temperature control accuracy: +/- 1 ℃
★ Temperature measurement accuracy: +/- 0.1 ℃
★ Control system: split type PID intelligent program section control, 40℃ high temperature red warning light reminds, temperature reaches yellow warning light;
★Time setting: 1min-999hR
Product features:
☆Diversified operation modes, to meet the needs of different experiments.
☆The temperature is as high as +/-0.1℃.
☆The heat preservation setting is calculated at 0.1℃.
☆The heating module and the control system are separated design, and the PID intelligent program segmentation control system.
☆A variety of heating and heat preservation options for your choice.
☆Driven by NanoHeat technology, the temperature rises to 5°C at an extremely fast speed, which only takes 1 second, and it only takes 20 minutes to reach 350°C.
☆No mechanical components, no electromagnetic field interference and harm, especially suitable for medical and laboratory use.
☆Save energy, the power consumption in standby state is less than 1W.
☆Suitable for most utensils, glass, ceramics, metal, all.
☆Easy to use, controller button design, digital screen display, safety lock, timepiece function, and high temperature alarm reminder, convenient for users.
☆Fashionable and beautiful appearance, luxurious atmosphere.
☆Anti-corrosion silicon carbide board, easy to clean.
(1) Technical indicators:
Project equipment name
HTL-400EXT
workbench size (material)
440*340 (high-density silicon carbide board)
400*300 (heating zone)
setting temperature
RT-360℃
temperature
controller split temperature control system, Intelligent PID program section control
temperature control accuracy
±0.1℃,
time setting
1min~999hr
working voltage
AC220V/50Hz
heating power
1.5KW
outline size
440*340*70
(three) after-sales service commitment
1) Quality assurance: manufacturer for sales The equipment undertakes quality assurance to protect the buyer's rights and interests from loss. If the equipment fails within the warranty period, the instrument will be provided with free warranty service (non-human factors), and the warranty period is one year.
2) Quality assurance service: The equipment within the warranty period can get free maintenance service and free replacement of broken parts.
3) Provide buyers with timely, prompt and high-quality services. A senior engineer hotline supports the buyer to troubleshoot on-site. The manufacturer will respond within 4 hours after receiving the relevant fault information, including verbal guidance and troubleshooting measures. If the fault cannot be eliminated, the manufacturer's personnel will go to the scene to solve the problem within 48 hours.
4) Technical support and excellent after-sales service provided by the manufacturer for the instrument; and free regular inspections and exchanges, 1-2 times a year.
(4) After-sales service
Shenzhen Boda Jingke Biological Technology Co., Ltd.
Address: Yantian, Shenzhen District, Yantianao Donghai Road West, No.447, Aokewei Building, 5th floor,
high temperature 500C° high temperature adjustable piezoelectric hot plate,
high temperature adjustable piezoelectric hot plate, adjustable piezoelectric
hot plate-five major-core technical advantages
1. The plate surface is made of German Schott microcrystalline ceramic or Silicon carbide board is resistant to various acids and alkalis and corrosion;
2. Nano thermal energy technology, fast heating, heating rate calculation of 5 degrees per second;
3. Nano ceramic heating element, super far-infrared heat radiation, strong penetrating power;
4. , a large heating area, uniform temperature; no mechanical heating element, no magnetic interference;
five, microcrystalline ceramic thermal shock heating panel 700 degrees, the expansion coefficient is equal to 0, and the length may be
continuously between dry;
a, the HTL series of laboratory Nano heating plate, adjustable piezoelectric heating plate,
natural marble casing, PTFE power cord and components, the whole machine is resistant to strong acid and alkali;
(1) Use:
laboratory nano heating plate is widely used in medical and health, agriculture, soil, and environmental protection , Food, scientific research institutes, universities and colleges and other experiments and laboratories. Can be used for sample heating, baking, digestion, acid removal, etc.
(2) Performance:
Adjustable electric heating plate HTL-400
Nano thermal energy technology, no mechanical heating components, dry burning, no electromagnetic field interference and hazards, rapid heating to 5 ℃, only 1 second, only 18 minutes to reach 500, greatly improving work efficiency;
technical parameters: model HTL-400
★ Heating fabric: glass ceramic (Schott, Germany) or silicon carbide board
★Heating method: Nano thermal technology (no mechanical heating components)
★Power demand: 220-240V AC, 50/60 Hz
★Output power: 3000W
★Product size ：440 (L) x340 (W) x 70 (H) mm
★Heating area: 400 (L ) x 300 ( W) mm
★Temperature control range: room temperature -500℃
★Control system: Infinite voltage regulator controller
Product features:
☆By Driven by NanoHeat technology, the temperature rises to 5°C at an extremely fast speed in 1 second, and it only takes 18 minutes to reach 500°C.
☆No mechanical components, no electromagnetic field interference and harm, especially suitable for medical and laboratory use.
☆Save energy, the power consumption in standby state is less than 1W.
☆Suitable for most utensils, glass, ceramics, metal, all.
☆Easy to use, stepless voltage regulator controller, convenient for users.
☆Fashionable and beautiful appearance, luxurious atmosphere.
☆Anti-corrosion silicon carbide or microcrystalline ceramic layer, easy to clean.
(1) Technical indicators:
Project name
HTL-400
workbench size (material)
440*340 (microcrystalline ceramics, silicon carbide plate)
400*300 (heating zone)
setting temperature
RT-500℃
temperature
controller stepless voltage regulation control
Temperature control accuracy Stepless
temperature adjustment
time setting
No
working voltage
AC220V/50Hz
Heating power
3.0KW
Dimensions
440*340*70mm