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Overview Article: Ammonium Bifluoride We have prepared an overview article on the chemical properties of Ammonium bifluoride.
The article gives a general description of ammonium bifluoride from the standpoint of chemical reactivity. It...
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Flame retardants are used to improve the fire resistance of materials.
Flame retardants are substances added to materials of organic origin to increase their fire-resistant properties. They slow down the combustion and ignition of the material.
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Classification of dangerous goods by hazard level (ADR hazard class) in Russia is based on GOST 19433-88 "Dangerous goods. Classification and labeling," introduced in 1990.
Classes of Dangerous Goods:
Class
Subclass
Name
1
explosive materials
1.1
explosives with a mass explosion hazard
1.2
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In industry, an important problem is the removal of scale and other deposits in pipelines, heating systems, boilers, and other equipment.
There is no universal technology for cleaning industrial equipment! The composition of the working solution depends on the composition of the deposits, the material the equipment systems are made of, and the type and technological features of the design.
In the food industry, “milk stone” and other specific deposits are also added to the mix.
Usually, the composition of the solution for chemical cleaning of industrial equipment is selected by a specialist after analyzing samples of the deposits.
During chemical cleaning of deposits, heating of the working solution is almost always required.
Scale in pipes
Let’s Look at the Main Products for Cleaning Pipelines and Equipment When Removing Scale:
A universal product for cleaning rust and scale. It also disinfects and removes mill scale.
It causes less metal corrosion compared to nitric acid and other aggressive acids.
Approximate description of working solutions based on Sulfamic acid:
Removal Methods:
– Milk stone — an aqueous solution with a concentration of 1.5-2%, 70-75°C, duration of use 30-40 minutes. Consumption — no more than 70 grams per ton of milk.
– Beer stone — an aqueous solution of 0.5-1.5 kg (1.5 kg for a layer thicker than 3mm) per 10 kg of water, application temperature 50-60°C, application time — 6-8 hours. After completion, rinse the equipment thoroughly with water.
Scale removal for heat exchangers (household, including radiators): a solution with a sulfamic acid concentration of 2-3%, 70-75°C, exposure time no more than 7 hours. It is recommended to add a corrosion inhibitor to the solution. After completion, rinse thoroughly with water (or a soda solution).
For equipment in pulp and paper production — a solution with a concentration of 10%, 25-45°C, time approximately 2-5 hours (until the concentration of the treatment solution drops to a minimum). The process can be carried out with recirculation. The working solution is not reused. Disposal of the solution — discharge into the industrial sewer system.
Removes oily deposits, as well as those consisting of calcium carbonate.
The downside is increased aggressiveness toward certain metals (for example, copper).
Approximate composition for removing calcium carbonate:
a 0.5% solution at a working temperature of 50-60°C, exposure time 15 minutes.
Protects against the formation of scale and rust. Degreases the surface. It is an alkaline product.
Effective for water with a calcium carbonate content of no more than 6 mg-eq/L.
In industry, a solution with a concentration of 50-100 g/L is used. For scale removal — 3-10 g/L.
An alkaline product. Used for removing scale deposits and corrosion.
Available in liquid and dry (powder or granules) form.
A hot solution must be used.
Excellently removes organic blockages.
The least hazardous to the human body. It is recommended to apply at a temperature not below 90°C. According to other data, scale removal begins as low as 60°C.
Not an oxidizer. Converts insoluble metal salts into soluble ones. An undeniable advantage — it does not damage plastic and rubber parts (gaskets, connections, and other elements).
An aqueous solution with a concentration of no more than 80 g/L is used.
— a 0.1/1% solution — 100 g per liter
Hydrochloric and Sulfuric Acids
Aggressive acids. They damage metal and pose increased hazard. But they also dissolve deposits most intensively. The cheapest acids.
Sulfuric acid is used for deposits with a calcium content of no more than 10%. Sulfuric acid also causes corrosion of copper.
Hydrochloric acid is used to remove carbonate deposits. Carbonate deposits must not be cleaned with sulfuric acid — upon reaction, the deposits will convert into even more poorly soluble sulfate-group compounds.
When Ammonium bifluoride is diluted with water, hydrofluoric acid is formed.
Hydrofluoric acid can also be used directly.
Used for phosphate and silicate deposits, which are quite difficult to remove with other products. Can be used on its own or as an additional component of the working solution.
Additional Steps:
During treatment, pieces of deposits fall off, so a second stage — rinsing with water — is mandatory. The rinsing speed must be sufficient so that particles of the detached deposits do not accumulate in pipe bends.
As a corrosion inhibitor, it is recommended to use Sodium tripolyphosphate, Sodium silicate, Zinc sulfate, Potassium dichromate, and others.
For Sodium tripolyphosphate, when used as a corrosion inhibitor, an aqueous solution with a concentration of 100 mg/L is used. The solution is used for several days. The flow speed of the solution should be no less than 0.3 m/s.
