*2.1. Impact Crusher*

The KU 80/120 impact crusher used in the technological system (Figure 3) was selected due to its advantages related to obtaining products with a lower content of irregular grains and higher strength of aggregates in comparison with products obtained from cone and jaw crushers [27]. Crushing occurs mainly due to the impact of material grains by the rotating slats attached to the rotor and the impact of the material accelerated by the slats on the stationary breaker plates. The adjustable gap between the rotor and plates allows for the adjustment of the size of the obtained fractions to the needs of the user. Properly selected materials, of which the slats and stationary plates are assembled, ensure their high resistance to abrasion, thanks to the low operating costs that the user incurs. Table 2 presents the characteristics of the crusher.

**Table 2.** Characteristics of the KU 80/120 crusher.


**Figure 3.** View of the KU 80/120 crusher and the WSR 3-2.0/6.0 screen. **Figure 3.** View of the KU 80/120 crusher and the WSR 3-2.0/6.0 screen.

#### **Table 2.** Characteristics of the KU 80/120 crusher. *2.2. Specialized Rotary Vibrating Screen (WSR)*

**Name Unit Value**  Inlet Size [mm] 800 × 1170 Rotor diameter [mm] 1110 Rotor length [mm] 1150 Capacity (maximum) [t/h] 450 Feed grain size range [mm] 0–700 Hard feed grain size [mm] 0–400 Crusher weight [kg] 11,851 Rotor weight [kg] 4136 Crusher drive power (max.) [kW] 250 Rotor Speed I [rpm] 529 Rotor Speed II [rpm] 670 *2.2. Specialized Rotary Vibrating Screen (WSR)*  Specialized rotary vibrating screen (WSR 3-2.0/6.0) (Figure 3) is a machine designed for screening the excavated material with transversely tensioned screens. The aggregate delivered to the screen deck is subjected to circular harmonic vibrations, where the material is periodically lifted under the force of gravity and moves along the screen deck. The elements causing the circular motion vibrations are rotating eccentric (shaft and inertial) masses. The vibrating force is directed at an angle of 15◦ to the base of the screen. The structure of the screen is shown in a schematic diagram in Figure 4. The technical characteristics are provided in Table 3. The screen is built in accordance with the concept of invention patented by AGH. It is an atypical screen (specialized) since it has three decks and produces six fractions. Its characteristic feature is first screening the feed material into fractions of 8–12 and 12–16 mm with the use of two decks equipped with square mesh screens, and then separating the irregular grains from the regular ones with the use of slot screens (rectangular mesh) (Figure 2). In the oversize-screen products, form aggregates are obtained, which, when joined together, form the innovative 8–16 mm RP (regular particles) products. In the undersize-screen products of these deposits, products with an increased proportion of 8–16 mm IP irregular particles are obtained after merging. Moreover, this screen separates the 0–8 mm fraction, which is fed to another specialized WSL screen, also to obtain the shaped aggregates. The fraction above 16 mm is a typical commercial product. *Minerals* **2022**, *12*, x FOR PEER REVIEW 6 of 15

creased proportion of 8–16 mm IP irregular particles are obtained after merging. Moreover, this screen separates the 0–8 mm fraction, which is fed to another specialized WSL screen, also to obtain the shaped aggregates. The fraction above 16 mm is a typical com-

**Name Unit Value** 

Working frequency [Hz] 16.6 Maximum stroke [mm] 9 Angle of screen inclination [°] 15 Drive power of screening unit [kW] 30

Motor rotation [rpm] 980 Maximum efficiency [t/h] 350

Screen deck 1 [mm] half deck-16 × 16 mesh,

Screen deck 2 [mm] half deck-12 × 12 mesh

Screen deck 3 [mm] half a deck-8 × 8 mesh

The raw materials selected for testing were various in terms of lithology and grain size distribution. Triassic dolomite, Triassic limestone, sandstone from the Carpathian flysch, gravel of river origin, and granite from the Central Sudety region were used. The graph (Figure 4) presents the particle size distribution curves of the feeds sent for crushing

Analyzing the grain size composition of the feed material (Table 4), it should be emphasized that the finest grain size range is the river gravel 0–63 mm and the largest share of coarse grains by limestone is in the range 14–80 mm. The content of out-of-form grains measured with a Schultz caliper in accordance with PN-EN 933-4:2008 [32] (SI shape index) in the feed varied and ranged from about 18% for dolomite to 25% for sandstone.

The raw material was crushed using an impact crusher at a rotation speed of 529/min. The outlet gaps between the strips and the impact plates were 20, 40, and 60 mm. The finest grades (S50) obtained were highest for dolomite and limestone (about 6) and lowest for gravel, which is related to the grain size of the feed. The particle size distribution

half a deck-blank screen

half deck-10 × (60) 75 gap

half deck-8 × (50) 60 gap

ticles) products. In the undersize-screen products of these deposits, products with an in-**Figure 4.** Particle size distribution curves of five feeds sent to the impact crusher. **Figure 4.** Particle size distribution curves of five feeds sent to the impact crusher.

**Table 3.** Characteristics of the WSR 3-2.0/6.0 rotary screen.

mercial product.

**3. Results and Discussion** 

in the impact crusher.

*3.1. Tests on Different Types of Raw Materials* 

curves of the crusher products are shown in Figure 5.


**Table 3.** Characteristics of the WSR 3-2.0/6.0 rotary screen.

#### **3. Results and Discussion**

#### *3.1. Tests on Different Types of Raw Materials*

The raw materials selected for testing were various in terms of lithology and grain size distribution. Triassic dolomite, Triassic limestone, sandstone from the Carpathian flysch, gravel of river origin, and granite from the Central Sudety region were used. The graph (Figure 4) presents the particle size distribution curves of the feeds sent for crushing in the impact crusher.

Analyzing the grain size composition of the feed material (Table 4), it should be emphasized that the finest grain size range is the river gravel 0–63 mm and the largest share of coarse grains by limestone is in the range 14–80 mm. The content of out-of-form grains measured with a Schultz caliper in accordance with PN-EN 933-4:2008 [32] (SI shape index) in the feed varied and ranged from about 18% for dolomite to 25% for sandstone.


**Table 4.** Characteristics of raw materials and operation of the crusher.

The raw material was crushed using an impact crusher at a rotation speed of 529/min. The outlet gaps between the strips and the impact plates were 20, 40, and 60 mm. The finest grades (S50) obtained were highest for dolomite and limestone (about 6) and lowest for gravel, which is related to the grain size of the feed. The particle size distribution curves of the crusher products are shown in Figure 5.

Table 5 summarizes the content of irregular grains in different fractions of products obtained from the impact crusher. The content of non-formed grains was measured using slotted sieves in accordance with the PN-EN 933-3:2012 [33] standard (flakiness index FI), with grains below 4 mm (outside the scope of the standard) included in the analysis for the purposes of the project. The formed irregular grains in the crushing process depend mainly on the physical and mechanical properties of the raw material (hardness, flakiness, toughness, structure, texture), but also on the type of crusher and its technical and technological parameters [34]. Therefore, it can be seen (Table 5) that the highest proportion

of irregular grains (from 15–25%) was observed in the finest fractions of 2–8 mm. This is a known phenomenon that aggregate producers have problems with, as the fine commercial grades are the most difficult to meet the standard requirements. The objective of this project was to reduce the content of unshaped grains to at least 3% in the Formator installation. The proportion of irregular grains also depends on the comminution degree of the raw material. It was observed that the highest content of irregular grains in the 2–8 mm class (FI = 25% sandstone, FI = 24% dolomite) was obtained for high comminution degree S50 values 6.7 and 4.5, and the lowest values FI = 15% (gravel), FI = 17% (granite) for the lowest comminution degree S50 values 3.3 and 3.9. Similar trends are found for the wider grain fraction 2–16 mm where the highest FI ratios are found for dolomite 17.8%, sandstone 16.2%, and limestone 15.2%. Here, the raw materials were crushed at the highest values of comminution degrees (Tables 4 and 5). **Raw Material Feed Grain Size [mm] Shape Index SI [%] Comminution Degree Crusher [t/h] Feed Crusher Product S90 S50**  dolomite 20–80 17.8 14.9 2.8 6.7 80 sandstone 25–80 25.3 13.5 2.8 4.2 80 gravel 0–63 24.3 13.6 1.8 3.3 60 granite 14–80 20.0 15.7 2.2 3.9 100 limestone 14–80 18.6 13.7 3.4 6.0 100

**Throughput** 

*Minerals* **2022**, *12*, x FOR PEER REVIEW 7 of 15

**Table 4.** Characteristics of raw materials and operation of the crusher.

**Figure 5.** Particle size distribution curves of five comminution products in an impact crusher directed to the WSR screen**. Figure 5.** Particle size distribution curves of five comminution products in an impact crusher directed to the WSR screen.


**Table 5.** Contents of irregular grains in individual fractions obtained in an impact crusher.

toughness, structure, texture), but also on the type of crusher and its technical and technological parameters [34]. Therefore, it can be seen (Table 5) that the highest proportion of irregular grains (from 15–25%) was observed in the finest fractions of 2–8 mm. This is a known phenomenon that aggregate producers have problems with, as the fine commercial grades are the most difficult to meet the standard requirements. The objective of this project was to reduce the content of unshaped grains to at least 3% in the Formator instal-The products obtained after crushing in the impact crusher were transported by a belt conveyor to the WSR screen, where they were sieved into fractions, 0–8, 8–12, 12–16, and +16 mm. The 8–12 and 12–16 mm fractions were sifted on slot screens (longitudinal rectangular mesh), from which regular and irregular grains are separated. These fractions are then combined with respect to shape into fractions of 8–16 mm RP (with regular grains) and 8–16 mm IP (with non-formed grains). Figures 6 and 7 present selected photographs of the product received. Figure 8 presents examples of the samples for analysis.

lation. The proportion of irregular grains also depends on the comminution degree of the raw material. It was observed that the highest content of irregular grains in the 2–8 mm class (FI = 25% sandstone, FI = 24% dolomite) was obtained for high comminution degree S50 values 6.7 and 4.5, and the lowest values FI = 15% (gravel), FI = 17% (granite) for the lowest comminution degree S50 values 3.3 and 3.9. Similar trends are found for the wider All of the obtained grain composition curves for the 8–16 mm sieving products of the upper-screening (RP) and bottom-screening (IP) are summarized in a graph (Figure 9). From the analyses, it can be concluded that granite with irregular grains had the finest grain size and dolomite with regular grains had the coarsest grain size. The 8–16 mm IP granite had the highest content of sub-grain up to 22%, which was not completely screened (outcrop of fractions below 8 mm). This is related to the higher throughput (about 100 t/h, Table 3). Comparing the remaining diagrams with each other, it should be stated that all

grain fraction 2–16 mm where the highest FI ratios are found for dolomite 17.8%, sand-

2–8 24.0 25.0 15.3 17.0 18.9 8–16 9.8 9.7 10.8 10.3 11.1 2–16 17.8 16.2 13.0 13.7 15.2 2–31.5 14.9 13.5 13.6 15.7 13.7

**Flakiness Index FI [%] Dolomite Sandstone Gravel Granite Limestone** 

**Table 5.** Contents of irregular grains in individual fractions obtained in an impact crusher.

**Crusher Product [mm]** 

values of comminution degrees (Tables 4 and 5).

of the passing material, i.e., those containing irregular grains, are considerably finer than the retained material on the screen surface, i.e., regular ones, as they contain about 10% of undersize. On the other hand, the retained material with regular grains contains from about 1 to 5% of undersize, which indicates the high quality of the aggregates. The content of 5% of sub-grain was recorded for limestone and granite with the screening capacity of about 100 t/h. and +16 mm. The 8–12 and 12–16 mm fractions were sifted on slot screens (longitudinal rectangular mesh), from which regular and irregular grains are separated. These fractions are then combined with respect to shape into fractions of 8–16 mm RP (with regular grains) and 8–16 mm IP (with non-formed grains). Figures 6 and 7 present selected photographs of the product received. Figure 8 presents examples of the samples for analysis. and +16 mm. The 8–12 and 12–16 mm fractions were sifted on slot screens (longitudinal rectangular mesh), from which regular and irregular grains are separated. These fractions are then combined with respect to shape into fractions of 8–16 mm RP (with regular grains) and 8–16 mm IP (with non-formed grains). Figures 6 and 7 present selected photographs of the product received. Figure 8 presents examples of the samples for analysis.

The products obtained after crushing in the impact crusher were transported by a

The products obtained after crushing in the impact crusher were transported by a

belt conveyor to the WSR screen, where they were sieved into fractions, 0–8 , 8–12, 12–16,

belt conveyor to the WSR screen, where they were sieved into fractions, 0–8 , 8–12, 12–16,

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*Minerals* **2022**, *12*, x FOR PEER REVIEW 8 of 15

**Figure 6.** Limestone tests 8–16 mm regular and irregular particles*.* **Figure 6.** Limestone tests 8–16 mm regular and irregular particles. **Figure 6.** Limestone tests 8–16 mm regular and irregular particles*.*

**Figure 7.** Sandstone tests 8–16 mm regular and irregular particles*.* **Figure 7. Figure 7.**  Sandstone tests 8–16 mm regular and irregular particles. Sandstone tests 8–16 mm regular and irregular particles*.*

Table 5 presents the content of irregular grains for the five final products (FI flakiness index). The final products are the retained material of the WSR 8–16 mm RP screen, on which regular grains retain. All of these products have flakiness indexes of less than 1.5%, the intended goal has been achieved and this means that the content of regular grains in these products exceeds 98%. The lowest contents were obtained for granite (0.2%), limestone (0.3%), and sandstone (0.5%). For gravel, the highest value was 1.3%. The content

of irregular grains for the product including under-screen (6.3–16 mm) was also calculated and ranges from 8 to 17%. Moreover, Table 6 summarizes the content of irregular grains that occurs in the screening product of the screen and comes from the process of sifting these grains on a given screening deck (irregular grains screened on the screen fall through its openings and accumulate in the screening product). In accordance with the idea of the invention, these products can be crushed again or used as aggregates. The values of the proportion of irregular grains are not high, as they range from 9% for granite to 17% for gravel. It can be concluded that these values have typical aggregates produced in processing plants [13,14,28]. The partial shares (6.3–16 mm) reduce the content of irregular grains by 1%, with the exception of limestone (increase by 0.4%). *Minerals* **2022**, *12*, x FOR PEER REVIEW 9 of 15

*Minerals* **2022**, *12*, x FOR PEER REVIEW 9 of 15

**Figure 8.** Final product: Limestone 8–16 mm regular (**left**), irregular (**right**). **Figure 8.** Final product: Limestone 8–16 mm regular (**left**), irregular (**right**). screening capacity of about 100 t/h.

gates. The content of 5% of sub-grain was recorded for limestone and granite with the

**Figure 9.** Particle size distribution curves of five screening products in the fraction 8–16 mm (WSR screen)**. Figure 9.** Particle size distribution curves of five screening products in the fraction 8–16 mm (WSR screen).

Table 5 presents the content of irregular grains for the five final products (FI flakiness index). The final products are the retained material of the WSR 8–16 mm RP screen, on which regular grains retain. All of these products have flakiness indexes of less than 1.5%, It is worth noting that the content of irregular grains in typical processing plants reaches about a dozen or more percent in coarse products, and in fine grains they often exceed 20%. For comparison, Table 7 summarizes the content of irregular grains for typical

the intended goal has been achieved and this means that the content of regular grains in these products exceeds 98%. The lowest contents were obtained for granite (0.2%),

**Figure 9.** Particle size distribution curves of five screening products in the fraction 8–16 mm (WSR

Table 5 presents the content of irregular grains for the five final products (FI flakiness index). The final products are the retained material of the WSR 8–16 mm RP screen, on which regular grains retain. All of these products have flakiness indexes of less than 1.5%, the intended goal has been achieved and this means that the content of regular grains in these products exceeds 98%. The lowest contents were obtained for granite (0.2%),

screen)**.** 

products obtained before refinement in the WSR specialized screen, i.e., these aggregates would be obtained if a typical vibrating screen was used in the technological system. The content of irregular grains would range from 10–11%. In addition, Table 8 summarizes the flow balance of the 8–16 mm product (mass yield) with separation into fractions with regular particles (RP) and irregular particles (IP).

**Table 6.** The flakiness index FI for the five final products of 8–16 mm of the *Formator* technological system.


**Table 7.** The flakiness index (FL) values of products received from conventional crushing and screening of plants compared with those received from the innovative one.


**Table 8.** Mass balance with separation into fractions with regular particles (RP) and irregular particles (IP).


## *3.2. Optimization of Required Machine Parameters*

As a result of the tests, the necessary operating parameters of the machines were optimized for their proper functioning. The most important issues included the solution of the problem of blocking of the mesh screens with difficult grains during the process of screening regular and irregular grains in the WSR screen. Difficult grains are grains of similar size to a given screen opening, which cause clogging of the sieves and a decrease of the screening efficiency. Due to the specificity of the technological process, each narrow fraction that is matched to the appropriate width of the slot contains 100% of grains difficult to sift. Therefore, the first screening tests were characterized by too strong blocking of the mesh with difficult grains, as shown in the photographs (Figure 10).

Factors affecting the efficiency of the screening process include [35–37]:


Since the last three factors cannot be changed due to the nature of the process, the solution had to be found in the dynamics of the screen. In vibrating screens, the movement of grain on the screen is caused by inertia forces, which are the result of periodic movement

of the screen. A value of vibration amplitude that is significantly low influences the lowering of screening process effectiveness by blocking of sieves with grains at a given output or lowering of screening output at assumed screening effectiveness. In screen machines, the transport of the material on the surface of the screen is usually achieved by means of vibrators causing harmonic vibrations or shafts with unbalanced masses, which are directed at an angle to the surface of the screen, while the screen can also be inclined to the horizontal. To parameterize the operation of the screen the dynamic index is determined, which is the ratio of the maximum acceleration of the screen to the acceleration of the earth. The dynamic index of the screen also informs the values of load of the screen construction by inertia forces. Depending on the type of screen motion, we use the feed rate (u1) (rectilinear screen motion) and toss index (u2) (circular, elliptical screen motion), which is the ratio of maximum screen acceleration to the acceleration due to gravity. *Minerals* **2022**, *12*, x FOR PEER REVIEW 11 of 15 screening regular and irregular grains in the WSR screen. Difficult grains are grains of similar size to a given screen opening, which cause clogging of the sieves and a decrease of the screening efficiency. Due to the specificity of the technological process, each narrow fraction that is matched to the appropriate width of the slot contains 100% of grains difficult to sift. Therefore, the first screening tests were characterized by too strong blocking of the mesh with difficult grains, as shown in the photographs (Figure 10).

**Figure 10.** Difficult grains blocking slot screen decks (toss index 4.4). **Figure 10.** Difficult grains blocking slot screen decks (toss index 4.4).

Factors affecting the efficiency of the screening process include [35–37]: For screens with circular vibration trajectory the toss ratio u<sup>2</sup> has the following form [35]:




ment of the screen. A value of vibration amplitude that is significantly low influences the **Table 9.** Operating parameters of WSR screen.


mined, which is the ratio of the maximum acceleration of the screen to the acceleration of the earth. The dynamic index of the screen also informs the values of load of the screen The best effect of sieve cleaning of "difficult" grains was obtained for a vibration radius of 6 mm, which raised the toss ratio to a value of 6.6 acceleration due to gravity. A photo of

u

construction by inertia forces. Depending on the type of screen motion, we use the feed

For screens with circular vibration trajectory the toss ratio u2 has the following form [35]:

*r*

*g*

where *r* is the radius of vibration, mm; *ω* is the angular velocity, rad/s; *g* is acceleration

due to gravity, m/s2; and *β* is the angle of inclination of the sieve to the horizontal.

cos

ω

2 <sup>2</sup> = >

β

1

(1)

**Figure 11.** Change of unbalanced masses on the eccentric shaft of the screen. **Table 9.** Operating parameters of WSR screen. **Radius of Vibration**  *r***, [mm] Angular Velocity** *ω***, [rad/s] Angle of Inclination of the Sieve to the Horizontal,** *β* **[°] Toss Index u2** 4 102.6 15 4.4 5 102.6 15 5.5 6 102.6 15 6.6 The best effect of sieve cleaning of "difficult" grains was obtained for a vibration radius of 6 mm, which raised the toss ratio to a value of 6.6 acceleration due to gravity. A photo of the conducted tests and the sieve cleaning effects are illustrated by the photo-

the conducted tests and the sieve cleaning effects are illustrated by the photographs shown in Figure 12. balanced masses on the shaft and study the cleaning of the sieves (Figure 11). The data are summarized in Table 9 along with the calculated toss ratio u2.

The pitch of the riddle is affected by unbalanced masses, which change the radius of

its oscillation. Therefore, this radius can be adjusted by adding or removing masses on the eccentric shaft. Since the radius of vibration measured on the riddle was 4 mm, which provided a toss ratio of more than 4.4, it was recommended to gradually increase the un-

The pitch of the riddle is affected by unbalanced masses, which change the radius of its oscillation. Therefore, this radius can be adjusted by adding or removing masses on the eccentric shaft. Since the radius of vibration measured on the riddle was 4 mm, which provided a toss ratio of more than 4.4, it was recommended to gradually increase the unbalanced masses on the shaft and study the cleaning of the sieves (Figure 11). The data are

*Minerals* **2022**, *12*, x FOR PEER REVIEW 12 of 15

summarized in Table 9 along with the calculated toss ratio u2.

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**Figure 11.** Change of unbalanced masses on the eccentric shaft of the screen. **Figure 11.** Change of unbalanced masses on the eccentric shaft of the screen. graphs shown in Figure 12.

graphs shown in Figure 12. **Figure 12.** Photographs showing the condition of sieve blockage with difficult grains: At a toss index of 5.5 (**left**), at a toss index of 6.6 (**right**). **Figure 12.** Photographs showing the condition of sieve blockage with difficult grains: At a toss index of 5.5 (**left**), at a toss index of 6.6 (**right**).

## **4. Conclusions**


**Figure 12.** Photographs showing the condition of sieve blockage with difficult grains: At a toss index

of 5.5 (**left**), at a toss index of 6.6 (**right**).

• Tests conducted on the crushing and production of molded aggregates in the innovative WSR screen have shown that aggregates produced from five different rock materials have very low FI flakiness indexes. • Tests conducted on the crushing and production of molded aggregates in the innovative WSR screen have shown that aggregates produced from five different rock materials have very low FI flakiness indexes. • The final products are the upper-screen products of the 8–16 mm RP deposits, on

• The installation produced at the Dolomite Mine in Imielin has innovative solutions in terms of products and processes, in accordance with the Oslo handbook [38]. It is a novelty that has not been used to date in the world due to its unique features and functionality as compared with the solutions available on the domestic (Polish) and

• By adjusting the appropriate dimensions of the screen (or screen decks), the capacity of the technological crushing and screening system can be increased by at least 30%. The increase in capacity depends on the content of regular grains, which can be taken out of the system as a final product, since there is no need to further crush them in

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#### **5. Patents 5. Patents**

**4. Conclusions** 

foreign markets.

other crushers.

The following patent granted in Poland is related to this paper: Author: Gawenda T.: Wibracyjny przesiewacz wielopokładowy, AGH w Krakowie. Patent No. PL 231748 B1 granted on 12 June 2018. The following patent granted in Poland is related to this paper: Author: Gawenda T.: Wibracyjny przesiewacz wielopokładowy, AGH w Krakowie. Patent No. PL 231748 B1 granted on 12 June 2018.

**Author Contributions:** Conceptualization, T.G.; methodology, T.G., A.S. (Agata Stempkowska) and D.S.; validation, D.F. and A.K.; formal analysis, T.G., D.S. and D.F.; investigation, T.G., A.S. (Agata Stempkowska), D.F., A.K. and A.S. (Agnieszka Surowiak); data curation, D.S. and D.F.; writing original draft preparation, T.G. and A.S. (Agata Stempkowska); writing—review and editing, T.G. and D.S. All authors have read and agreed to the published version of the manuscript. **Author Contributions:** Conceptualization, T.G.; methodology, T.G., A.S. (Agata Stempkowska), and D.S.; validation, D.F. and A.K.; formal analysis, T.G., D.S., and D.F.; investigation, T.G., A.S. (Agata Stempkowska), D.F., A.K., and A.S. (Agnieszka Surowiak); data curation, D.S. and D.F.; writing—original draft preparation, T.G. and A.S. (Agata Stempkowska); writing—review and editing, T.G. and D.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** The paper is the effect of completing the NCBiR Project, contest no. 1 within the subaction 4.1.4 "Appliaction projects" POIR in 2017, entitled "Elaboration and construction of the set of prototype technological devices to construct an innovative technological system for aggregate beneficiation along with tests conducted in conditions similar to real ones". The Project is co-financed by the European Union from sources of the European Fund of Regional Development within the Action 4.1 of the Operation Program Intelligent Development 2014–2020. **Funding:** The paper is the effect of completing the NCBiR Project, contest no. 1 within the subaction 4.1.4 "Appliaction projects" POIR in 2017, entitled "Elaboration and construction of the set of prototype technological devices to construct an innovative technological system for aggregate beneficiation along with tests conducted in conditions similar to real ones". The Project is co-financed by the European Union from sources of the European Fund of Regional Development within the Action 4.1 of the Operation Program Intelligent Development 2014–2020.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. **Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest. **Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

