PVDF (polyvinylidenefluoride or polyvinylidenefluoride) is a thermoplastic fluoropolymer. PVDF resins are generally found in the form of granules and can be used in compounding, moulding and extrusion, like standard thermoplastic polymers and fine powders.

PVDF is a partially fluorinated thermoplastic polymer whose chemical characteristics make it applicable to many materials used in various industries, such as food and medical.

Precisely for this reason, several customers have turned to STM Microtec to carry out milling and micronising tests on this material, requiring very specific and difficult grain size targets. In particular, unlike other polymers that are ground in cryogenics, PVDF does not require this.

In fact, a machine from the Galileo Line, a highly innovative multi-function laboratory plant from a technical point of view, was used, and more specifically the MJS Jet Mill gas (air/nitrogen) counterjet refining mill.

The tests conducted allowed STM Microtec to thoroughly analyse its characteristics in order to emphasise its special features.

STM’s micronisation process can cause PVDF to first become a 200/300 µm granule, and then be further reduced until it reaches 30 µm, resulting in an extremely fine granule. These polymers are anomalous: they have a lower strength and therefore, unlike polyethylene and PVC, grinding can take place at room temperatures, as in this case. Grinding at room temperature has the peculiarity of enhancing the physical-morphological characteristics of the material.

STM, thanks to the excellent performance of its machines, is able to obtain a controlled, homogeneous, repeatable process that produces process output appropriate to the customer’s requirements.

In conclusion, the results obtained show that the efficiency of the STM Microtec machines allowed an excellent performance in terms of granulometric reduction quality, process continuity, thanks to the elimination of the undesired electro-static qualities of the PVDF, and versatility, thanks to the possibility of fielding the STM technology most suitable for the output requested by the customer.

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STM Microtec will be present at Pollutec 2023

From October 10th to 13th, STM Microtec will be in Lyon, France, to participate in Pollutec, the international trade fair for environmental solutions.

During the event, STM Microtec, a leader in environmental technologies with over 500 successful installations in the field of air purification, will showcase its cutting-edge solutions for the reduction of pollutants from industrial and production processes. These patented technologies and fully digitized systems play a crucial role in driving towards a more environmentally sustainable perspective in compliance with the strictest environmental regulations for gas emissions and production effluents.

With years of experience, STM Microtec is capable of assessing and identifying the best emission reduction system based on the type of pollutant, its concentration in the gas stream, and the specific production line requirements. This ensures both productive efficiency and cost-effectiveness while guaranteeing uninterrupted operation for at least 6000 hours without downtime.

In the context of dry milling and injection of sodium bicarbonate to reduce sulfuric and acidic emissions from fossil fuels, STM Microtec will present one of its flagship machines at Pollutec: BICARMILL®. This fully autonomous “plug & play” machine represents the perfect combination of STM Microtec’s mechanical and electronic technology, offering unparalleled reliability, productivity, and energy savings. Housed in a soundproof box with a PLC and remote connection, a sodium bicarbonate dosing system feeds a complete impact mill with a classifier. Through perfect control of airflow, Bicarmill® maintains an ideal particle size distribution (resulting in a PSD d.90<20µm; d.50<6µm d10<1µm) for emission reduction with a perfect stoichiometric injection ratio at both low and high reagent flow rates, effectively neutralizing acids in emissions, even during peak pollutant levels. Additionally, by maintaining a controlled operating temperature below 50°C, with an average of 45°C, the machine prevents reagent degradation, ensuring an ideal chemical reaction in the reduction process.

Depending on the operating conditions of systems for controlling acidic substances in emissions, hydrated lime represents a valid alternative to sodium bicarbonate. Although it does not require milling, hydrated lime can be cohesive and highly hygroscopic. STM Microtec provides dosing and injection solutions specifically designed for hydrated lime, ensuring maximum dosing accuracy and preventing line blockages and clogs. This is achieved through a fan directly connected to the dosing system, replacing the traditional use of venturi ejectors or rotary valves.

For applications dedicated to heavy metal emissions control, such as mercury, dioxins, and furans, at Pollutec, you can explore STM Microtec’s solutions for dosing and injecting activated carbons, both brominated and non-brominated. These ATEX-certified systems integrate dosing skids with pneumatic transport based on venturi ejectors, ensuring a continuous injection into the flue duct. Activated carbon dosing requires continuity and high precision. Given the low specific weight and cohesiveness of the material, this can lead to dosing inaccuracies. STM Microtec installs weighing platforms on its reagent dosing systems to control the quantity and uniformity of injection, with automatic flow adjustment using a “loss in weight” system and the use of a Venturi Ejector, which, thanks to the vacuum generated at the loading mouth, prevents any spillage without disrupting the dosing process.

STM Microtec is proud to be a key player in promoting solutions for a cleaner and more sustainable environment. We continually work to overcome ever-evolving challenges and make a positive impact on our community and the global environment. Come and visit us; our specialists await you at booth H5-A036!

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The plastics processing industry is constantly striving to improve the efficiency of production processes and ensure the quality of finished products. One of the crucial aspects in this industry is the addition of additives and functional materials, such as potato starch, to plastic films during the extrusion process. In this article, we will examine a case study regarding the implementation of microdosers for adding potato starch to plastic film after extrusion, and discuss the benefits and challenges associated with this technology.

Analysis of customer needs

The customer, who turned to STM Microtec, uses an extrusion process of two sheets of film which are then joined together. However, the process is characterized by considerable variability, and extruded film production can vary significantly throughout the day.
The customer had previously installed several screw feeders, but these devices were not performing in terms of quality and consistency of the dosing, limited dosing range and lack of an integrated operating logic to the machine.c

Testing and data analysis

To better understand the dynamics of the customer’s process and identify the most suitable solution for their needs, STM Microtec conducted a series of tests in its laboratory, simulating the customer’s process and using part of the customer’s plant.
After collecting and analyzing the data obtained from the tests, STM Microtec evaluated, using calculation algorithms, the most suitable dimensioning of the machine for the customer.

Machine design in synergy with daily use

The machine designed by STM Microtec was designed to be used daily and continuously, in an application where food compatibility is required. This is possible thanks to:
– Robust body in stainless steel
– Parts in contact with the material are in food silicone.
– The grease used for the rotation bushings is completely food grade.
– The storage hopper, suitable for containing a 25 kg bag, has an ideal angle of inclination even for less flowing products.
– The hopper opening is equipped with an easy charging system, which facilitates the sliding of the product through the protective grid.

Precise and constant dosage

The internal agitator reel of the machine has been designed to avoid compacting the material and keep the product arriving at the dosing screw fluid. The dosing of the product was the main challenge of the project, as it was necessary to guarantee a wide dosing range and a dosing precision of less than 2%.
The coaxial thruster was another challenge of the project, as it had to guarantee the smooth and continuous flow of the product in a restricted section of pipe and with maximum pressure parameters very limited by the customer, for technical reasons. STM also managed to pass this test, providing a system that was also easy to maintain, which the customer had never evaluated and which was greatly appreciated.

Management by DCS and remote assistance

The dosing system provides for the possibility of choosing between pre-compiled recipes and DCS management of all machine parameters. Furthermore, there is a remote assistance module installed in the electrical panel, allowing quick interventions in case of need.


The implementation of microdosers for adding potato starch to plastic film after extrusion can lead to significant benefits in terms of dosing quality and consistency, wide dosing range and ease of use. Through close collaboration between STM Microtec and the customer, it was possible to design and build a machine that responded perfectly to the specific needs of the application, significantly improving the efficiency of the production process and the quality of the finished products.

Click here to discover our microdosers.



The word ‘nutraceutical’ refers to a range of products whose main purpose is to support the body’s physiological processes. They are mostly substances of natural origin, particularly plants, but also vitamins, minerals and other chemically synthesised substances.


In recent years, there has been a growing interest in algae in various nutraceutical and pharmaceutical formulations that can confer significant health benefits.


In particular, due to its nutrient concentration, spirulina has been recommended by NASA and the European Space Agency (ESA) as one of the foods to be taken during long-term space missions.

Algae could be the ‘future of food’ then, just think that in Italy, demand for dried microalgae stands at around 200 tonnes for uses ranging from food and nutraceuticals to cosmetics and pharmacopoeia.

Nutrients are more effectively assimilated when properly micronised and they can also be extracted and used for food supplements or added to food.

Depending on the type of results to be obtained, STM Microtec is able to offer various technologies for grinding algae.



Grinding with the MP series impact mill, equipped with special grinding elements, is able to free the cell walls, with its friction and shear action, in an anhydrous circuit controlled by temperature and process humidity.



From the grinding process, the product is conveyed to a dynamic separator, where the final part is easily collected, with an average particle size d.90<30µm, while the coarse particles return to the process, making the cycle without product loss.



The milled and sorted product can be further refined with an MJS series, an air mill with opposing jets and integrated screening, to achieve better quality and fineness of particle size.

With an average particle size d.90<10µm and a d.99<20µm



Possibility of mixing, by means of a multi-dosing station, with volumetric micro-batchers, with loss-in-weight dosage control, for a perfect blend that adapts to heterogeneous products while guaranteeing perfect recipe dosing.

This can be done either before or during the grinding process, with 2 or more elements to be ground entering the line.

Grinding helps to amalgamate the compounds with concentrated nutraceutical extracts while micronising allows for better suspension of the compound at extra fine particle sizes.


In conclusion, based on the specific requirements of particle size output, dosing, microniser lab scales and milling production plants, both in terms of the technology used and the fineness extracted, STM Microtec can offer extremely adaptable solutions for each individual and specific need.  From 1 kg/h to higher productivity industrial plants.

Product analysis and characterisation: a valuable service that can improve your plant performance

Product analysis and characterisation: a valuable service that can improve your plant performance


thanks to state-of-the-art instrumentation and a team of specialists, STM Microtec has a laboratory that is able to process a product analysis that includes all those physical and chemical characteristics relevant to the transformation of the materials to be micronized and selected.


The results can be very valuable for optimising plant performance: it is a complete study and characterisation of the product. In the STM Microtec laboratory, not only particle size analysis is carried out, but also a broad spectrum of physical analyses relating to the state of matter, such as micrographic and morphological analysis. Everything is done by using dedicated and specific equipment and instrumentation, from slip control, to chemical moisture analysis, as well as the protein content of food flours.


Other advantages of the STM laboratory include rapid sample control, reduced product analysis costs and constant physical analytical support of milling and sampling results.


Rapid and complete product characterisation

STM Microtec’s laboratory therefore offers an analysis service for ultra-fine powders and characterisation of target samples, as well as active support for plant and technical development.


In a changing and rapidly evolving market, analytical feedback and the choice of technologies is crucial, but so is the speed of activation and the readiness to process results.

STM Microtec offers support for the research and development of micronized materials, assisting customers in the study phase and in the choice of the most suitable technologies for the type of product to be treated.


In Italy, the Company can offer analysis directly on field, at the customer’s facility, thanks to a mobile laboratory suitable for on-line connection, particle analysis and technical adjustments directly on the existing plant. Thus being able to provide immediate improvement solutions and a long-term integration plan of the most suitable technologies to maximise our customer’s productivity.

The benefits of cryogenic grinding for recycling tyre and rubber

Discover the benefits of cryogenic grinding for recycling tyre and rubber

In the last years, more and more companies have turned to an environmentally sustainable business model. One sector that has emerged in this field is the recycling of used and worn tyres, also as a result of EU regulations on the recycling and recovery of end-of-life materials.

On an industrial level, pulverising processes that are traditionally carried out at room temperature can be conducted at cryogenic temperatures with the aim of obtaining a better quality of the ground product and less energy consumption.

That is why products which have low softening points, elasticity and thermosensitive characteristics due to the presence of elastomers, such as tyres, are efficiently grinded by bringing them to their embrittlement temperature using liquid nitrogen.

Cryogenic grinding is successfully used in the milling processes of rubber and elastomer scrap and in all areas where cryogenics is more efficient, without damaging the physical-chemical or cross-linked structure of the finished product.

Cryogenic Application – Liquid Nitrogen

Liquid nitrogen has three main functions: it rapidly cools the material to embrittlement temperature before it enters the grinding mill. It keeps the processing temperature constant by absorbing heat developed during the grinding operation.

Cryo ground substances have different physical characteristics from those obtained by traditional grinding processes, precisely because of the way in which the structure of the material is broken down.

Here are the main differences between the two processes:



– Cryogenically embrittled tyre rubber produces homogenous, crystalline, cubic grains;

– Better production yield

– Better final product quality, without brittleness or breakage

– Reduced energy consumption

– Increased quality of finished product

– Less processing waste (due to overheating)

– Greater product fineness and homogeneity

– Reduction in the amount of material to be reprocessed



– Tears in the initial matrix due to the smoothness of the crystalline planes or special lattice structures

– Powders with non-uniform physical characteristics

– High energy consumption due to low hourly output

– Possibility of material melting on grinding rotors

– Low quantity of fine particles

– High recycling of materials above the sieve.

But what are the most relevant parts of this process? Let’s see how they work and what the main solutions involved are for.

Overhead receiving hopper and dosing unit integrated into the structure

The entire system is designed to contain and utilise cryogenics only at a specific point in the plant, the other areas work at room temperature such as the containment hopper  and the dosing hopper,.

Control is carried out by means of sensors, valves and metal detectors to correctly monitor the material.

Metal detector

By its nature tyre powder contains various metal contaminations, a good defection system, either simple or more advanced, is necessary for preserving the grinding tools.

Liquid Nitrogen Proportional Valve

It controls through electronic PID regulation the amount of liquid to be injected into the circuit, working in synchrony with the recovery of cold gases and the working temperature of the grinding chamber.

Special cast counter rotating impeller

Highly efficient grinding impellers with wear-resistant discs and cylindrically shaped cast pegs, specially designed for highly abrasive polymers.

Easy access to the grinding chamber and simple replacement of pins and wear parts due to the coupled disc construction are the strengths of this solution.

Nitrogen, which is connected via a hose to the cryogenic screw, is atomised via nozzles on the rubber.

The controlled working temperature ensures maximum efficiency of the system, the elevated position without pipeline handling of the product, and the shape contained in the armaflex shell allows the operating frigour to be maintained and processing energy to be optimally utilised.

Case Study STM: MPC 400

The Contraplex MPC400 counter-rotating pin mill has a tyre powder output of approx. 500 kg/h at a grain size of 100%<500µm

The ideal working temperature is approx. – 28°C and the thermal insulation conditionsallow for low management consumption as well as the possibility to recycle non-exhausted cold gases.

This mill was integrated into customer’s production line, the sieved product was then placed in the big bags. The over sieve > 500µm is small and there is thus a recycling of low quantities that do not and vary the productivity of the raw material.

In conclusion, after the collection and block shredding phase, and the 5mm grain milling with 99% elimination of textile and metal fibres thanks to the STM Microtec plant, a 100% cryomacination <500µm was achieved.


This year STM Microtec decided to support Fondazione Giacomo Ascoli Onlus that provides the most qualified medical assistance and psychological support possible to children and adolescents suffering from onco-haematological pathologies, to guarantee them greater chances of recovery and the best quality of life during treatment at the Onco-Hematology Department of the Del Ponte Hospital in Varese (Italy).

May this holiday season be filled with peace, health and positivity!

Our offices are closed from 27th to 30th December.

See you in 2023!





During the end of year party, it was illustrated how in 2022 STM continued its growth path in name of the 4 essential pillars on which the whole group is based: #innovation, #humanresources, #digitalization and #sustainability.

It was, as always, a pleasant moment for meeting, discussing and witnessing the successes achieved.

We are ready and thrilled to face the goals and new challenges we have set ourselves for 2023.





Since 1971 STM Microtec has been providing integrated solutions and tests for grinding and dosing. A wide and complete range of customized services, from single machines to complete packages for numerous industrial and environmental applications.


STM stands out for its concept of intelligent work in a dynamic world, where low-cost research with high physical and chemical data acquisition is essential to take into account new production possibilities.


The Laboratory Line represents the ideal choice for a research and development department and for companies with limited production quantities but of high-quality standards.


With its autonomous workstation, the pilot mill is a true autonomous and multifunctional laboratory plant that is highly innovative from a technical point of view.

The operating principle of the installed machines is the same as that of industrial production machines.

The possibility of testing the micronization on a small scale guarantees the transfer of the laboratory process to an industrial scale machine, thanks to the identification of the grinding mill, and a linear and precise increase in the machine production factor.


The GALILEO LINE offers 3 different functions:

  1. MJS – compressed gas jet mill (air / nitrogen);
  2. JCF – impact grinding mill;
  3. SDF – separation and classifying mill.


The three machines are specially designed for the production of small batches, the equipment and electronic devices used follow high design standards and the technology applied is at the forefront. The mechanical part is integrated with a series of electronic devices integrated as well into the transformation process to analyze the process parameters and the analytical recovery of p physical, chemical and mechanical data received by the instrumentation during the grinding of the product.


The ZERO LINE consists of:

  1. MDS – dosing system with volumetric augers and gravitational weight control;
  2. CLC – Cryogenic Auger (Liquid Nitrogen System);
  3. PIN – Mulino a Pioli – Pin Tool;
  4. NET – Mulino a Rete – Net Tool;
  5. EV – Venturi Ejector – Propulsion.


The operating principle and the conformation of the working chamber allow the application of cryogenic grinding or cryopulverization systems, for the artificial embrittlement of tenacious products at room temperature.


The STM Lab Line offers an ideal solution for obtaining process parameters, thanks both to the extreme quality of the granulometric results and its versatility.


STM has a Pilot Plant equipped with an efficient Laboratory where it can simulate and verify the performance of its technologies, varying the input material and the operating and process parameters by adapting the solutions to every need.





Nutrition is a powerful mean of prevention and a fundamental tool in dealing with everyday life. The increased awareness of the importance of a balanced diet and the use of natural products has led to greater use of high protein flours.


These are flours with a high concentration of proteins and fibers and with a very low content of carbohydrates and fats used both in bakery and pastry, and in the production of superfoods and sports foods, as well as vegetable powders for the production of scrubs or for make up.


STM has always collaborated with the food, parapharmaceutical and cosmetic industries to obtain high protein flours that retain the fundamental organoleptic properties and have a higher protein value than the starting material.


Particularly suitable for this sector is the JCF series grinding and selection mill combined with the SDF dynamic classifier, for maximum protein extrapolation.


JCF Impact Mill

It consists of a horizontal geometry grinding unit and specific tools for this application, shaped to provide maximum efficiency between grinding impact and product ventilation.

The ground particle passes through a selection sieve in a single compact machine, with a determinable and constant particle size 100% <50µm.


SDF dynamic classifier

The milled product enters the separation chamber, where the forced dynamic rotation between the static rotor and the dynamic classifier with adjustable rotation are able to divide and extract a significant amount of extra fine particles 99% <20µm.

SDF is integrated to the instrumentation for detecting the protein content, through an in-line analyzer.

The classifier unloading cone, makes the coarse product with fraction 20 ÷ 50 µm flow easily, while the finer dust is collected in the dedusting filter.


The JCF impact mill allows you to adjust the grinding parameters so that the flours are grinded to the necessary fineness with a high concentration of protein powders and the in-line separation of the coarse product poor in proteins.

The operational advantages of the JCF mill are:

  • Maximum energy efficiency
  • Low noise emission
  • Minimum maintenance
  • Compact machine, minimum space required
  • High reliability and quality of the system
  • Easy cleaning and maintenance
  • Reliability
  • Grinding of a wide range of materials
  • Possibility of temperature conditioning.


The machine can be easily opened for checks, cleaning and maintenance as it is equipped with a pneumatic mechanism that facilitates the opening of the grinding and classification chamber.


Do you want to learn more about JCF? Contact us.