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1

Investigation on the particle size and shape of iron ore pellet feed using ball mill and HPGR grinding methods

Abazarpoor A., Halali M.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

908--919

EN

An effect of a grinding method, that is ball mill and high pressure grinding rolls (HPGR), on the particle size, specific surface area and particle shape of an iron ore concentrate was studied. The particle size distribution was meticulously examined by sieve, laser and image analyses. To measure the specific surface area of particles, Brunauer-Emmett-Teller (BET) and Blaine methods were used. It was found that for samples having equal Blaine specific surface areas numbers, the amount of fine particles produced in HPGR was higher than that produced in a ball mill. A higher surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. A shape factor of particles was determined using the circularity, roughness, and aspect ratio. It was also observed that HPGR produced particles that were more elongated, less circular and rougher than those processed by the ball mill.

2

Comparison of grinding characteristics in high-pressure grinding roller (HPGR) and cone crusher (CC)

Liu L., Tan Q., Liu L., Li W., Lv L.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1009--1022

EN

We comparatively studied the ball mill grinding characteristics of comminuted hematite products using a high-pressure grinding roll (HPGR) and a conventional cone crusher (CC). The major properties, including grinding kinetics and technical efficiency (Et), were investigated. The parameters in m-th order grinding kinetics were analyzed, and grinding specific rates were visualized. Ore particles experienced three inherent stages in ball grinding mills, that is i) rapid grinding of coarse fraction, ii) dynamic grinding of medium size fraction, and iii) single grinding of medium size fraction. Particles with size -0.043+0.031 mm were used into dynamic grinding stage earlier than particles -0.105+0.043 mm, and then over-grinding of fines occurred easily. Compared with CC products, HPGR products had significantly shorter turning time points in three breakage stages, implying that HPGR products were ground faster with earlier occurrence of fines over-grinding. HPGR products gave lower Et at a decreasing rate than the CC products for -2.0 mm and -0.5 mm feeds. Then, it showed a slightly higher value of Et for -2.0+0.5 mm feed. This indicated that fines over-grinding in HPGR full-size products were more serious under the condition of coarse grinding, whereas the efficiency was higher, and over-grinding weakened significantly in HPGR coarse products because of screening-out fines.

3

Influence of type of lining in high-pressure grinding rolls on effectiveness of copper ore comminution

Saramak D., Foszcz D., Gawenda T., Konieczny A., Pawlos W.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

182--192

EN

Comminution in a High-Pressure Grinding Rolls (HPGR) device is considered as one of the most efficient method to break particles, in terms of the energy utilization. Two main types of the rolls linings are applied in hard ore grinding: studded and hexagonal, which show varied characteristics of operation and have different lifetime of service. The article concerns the analysis of HPGR device operation for various linings of the rolls. Two pilot-scale test programmes were run and performance of both types of rolls was tested in terms of energy consumption, technological effects measured by means of comminution ratio, lifetime service as well as economic aspects. Results of investigation show, that much longer lifetime service was obtained for the studded rolls, while hexagonal ones are more favourable from economic scope. The feed material for the HPGR comminution tests was Polish copper ore from two divisions of processing plants of KGHM Polska Miedz S.A. Taking into account that industrial comminution operations in mining and mineral processing sector consume over 50% of total energy utilized for ore treatment operations, the problem is of a major significance, especially in terms of optimization of hard ore crushing and grinding circuits.

4

Comparative study on the effect of using conventional and high pressure grinding rolls crushing on the ball mill grinding kinetics of an iron ore

Barani K., Balochi H.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

920--931

EN

The effect of using conventional and high pressure grinding rolls (HPGR) crushing on the ball mill grinding of an iron ore was assessed to determine how these different comminution processes affect the ball mill grinding kinetic. For this purpose, the sample was obtained from the Jalalabad Iron Ore Mine and crushed by conventional crusher and HPGR. Then, the crushing products were ground in a laboratory ball mill. Five single-sized fractions of (–4+3.15 mm), (–2+1.7 mm), (–1+0.850 mm), (–0.500+0.420 mm), and (–0.212+0.180 mm) were selected as the ball mill feed. The specific rates of breakage (Si) and cumulative breakage distribution function (Bi,j) values were determined for those size fractions. It was found that for all fraction the Bi,1 values of the HPGR product were higher than those for the crusher product. It means that the particles produced by the dry ball milling of the HPGR product were finer than by the crusher. Also, the results showed that the specific breakage rate of the material crushed by HPGR at coarse fractions (–4+3.15 mm, -2+1.7 mm, and -1+0.850 mm) was higher than the material crushed by conventional crushers. However, at fine fractions (–0.500+0.420 mm and -0.212+0.180 mm), there was a small difference and the specific breakage rates were the same. This issue can be explained by the fact, that for coarse fractions the particles had longer side surfaces and thus were more affected by the lateral pressure. The results of verification test showed that after 60 seconds of grinding the 80% passing size of the HPGR and crusher products (D80) were reduced from 3311 μm to 760 μm and 1267 μm, respectively.

5

Optimization of HPGR-Based Clinker Grinding Circuit at Abyek Cement Plant Using Steady-State Process Simulations

Farzanegan A., Sepahvand E., Mirzaei Z. S.

Inżynieria Mineralna

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2016

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R. 17, nr 2

255--260

EN

Abyek cement plant is equipped with four clinker grinding lines; every grinding line consists of a two-compartment tube ball mill. Recently, in a retrofit project, two high pressure grinding rolls (HPGR) units were installed in two grinding lines before the tube ball mills to grind clinker feed. The efficiency of these HPGR units is reported to be under design specification. In this study, an approach based on population balance modelling of grinding process and circuit simulations was used to optimize HPGR milling operation. Representative samples were taken from HPGR units’ feed and product streams to obtain HPGR model parameters, namely, breakage distribution function and selection function or specific rate of breakage. Screen analysis tests were carried out to determine Particle Size Distribution (PSD) of every powder sample and its d80 as powder size index. Tumbling grinding tests with laboratory ball mills were also done using collected samples to determine breakage distribution function of feed to HPGR units. Selection function was estimated based on PSDs of HPGR feed and product samples using NGOTC program. A comparison between HPGR measured and predicted product PSDs proved validity of modelling and simulation approach. Several simulation trials were performed to find the best settings of main input variables including applied roll pressure, roll gap and rolls rotational speed which showed that their optimal values are 180 bar, 0.01300 m and 2 m/s, respectively. Plant implementation of these settings for one of the HPGR units showed a 22% decrease in d80 of product. The optimization study indicates that production capacity can be increased from 150 t/h to 180 t/h with a Blain fineness of 3000 cm2/g.

PL

Cementownia Abyek jest wyposażona w cztery linie mielenia klinkieru; każda linia składa się z dwóch młynów kulowch. Ostatnio w projekcie modernizacji, zainstalowano dwie prasy ciśnieniowe HPGR usytuowane w ciągu technologicznym przed młynem kulowym. Skuteczność HPGR ocenia się na podstawie założeń projektowych. Badania oparto na modelowaniu bilansu procesu rozdrabniania w prasie i symulacji procesu. Reprezentatywne próbki pobrano z nadawy i produktów rozdrabniania w HPGR, celem było określenie parametrów modelu - funkcję rozkładu spękań oraz funkcję rozdrobnienia. Badania analityczne przeprowadzono w celu określenia rozkładu wielkości ziaren każdej próbki i jego D80 jako wskaźnik wielkości ziaren. Określono również wielkość ziaren metodą analizy obrazu na szlifach pobranych próbek. Funkcja selekcji została określona za pomocą programu NGOTC. Porównanie zmierzonych i przewidywanych wyników rozdrabniania w HPRG wykazało dokładność modelowania i symulacji. Liczne badania symulacyjne przeprowadzono w celu znalezienia optymalnych parametrów zmiennych wejściowych w tym ciśnienia i prędkości obrotowej. Badania wskazują, że optymalizacja zdolność produkcyjna może zostać zwiększona z 150 t/h do 180 t/h, z powierzchnią właściwą Blaina 3000 cm2/g.

6

Symulacja efektów rozdrabniania w prasie walcowej dla materiału o zmiennej zawartości ziaren drobnych

Saramak D.

Gospodarka Surowcami Mineralnymi

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2015

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T. 31, z. 2

123--136

PL

W artykule przedstawione zostały wyniki badań dotyczących procesów rozdrabniania w prasie walcowej dla rud miedzi. Przeprowadzono próby kruszenia w laboratoryjnej prasie walcowej dla materiału o zmiennej zawartości najdrobniejszych klas ziarnowych, mianowicie: od 0 do 6 mm, od 0,3 do 6 mm, od 1,5 do 6 mm oraz od 2,5 do 6 mm. Próby przeprowadzono dla materiału o wilgotności naturalnej (tj. blisko 0%) oraz 2%. Uzyskane w tym zakresie wyniki pokazują, że dla materiału wilgotnego efektywność rozdrabniania nieznacznie się zmniejszyła, również pozbawianie nadawy kolejnych drobnych klas ziarnowych miało swój efekt w mniejszym stopniu rozdrobnienia produktów HPGR, jednak w miarę dalszego zwiększania wilgotności nadawy wskaźniki wydajności oraz energochłonności procesu uległy pogorszeniu. Analizując parametry pracy wysokociśnieniowej prasy walcowej można stwierdzić, że zwiększenie wilgotności nieznacznie zwiększa wydajność procesu, również w niewielkim stopniu redukując jego energochłonność. [...]

EN

The article presents the results of investigations over the comminution processes in HPGR for copper ore. Crushing tests were run in a laboratory HPGR device for the material with a variable content of fine particles in following size fractions: from 0 to 6 mm, from 0.3 to 6 mm, from 1.5 to 6 mm and from 2.5 to 6 mm. The tests were performed for the material with moisture content of 0 and 2%. The obtained results show that comminution effectiveness for material with an increased moisture content decreased slightly. Also the removal of individual finest particle size fractions from feed had its effect in a lower comminution efficiency, and increasing the feed moisture caused deterioration of the energy and capacity indices for the process. Analyzing the HPGR operating parameters it can be concluded that together with increasing the moisture content the process productivity slightly increases, together with some reduction of its energy consumption. [...]

7

First year of operation of HPGR at Tropicana Gold Mine – Case Study

Gardula A., Das D., DiTrento M., Joubert S.

Cuprum : czasopismo naukowo-techniczne górnictwa rud

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2015

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nr 2

15--36

EN

AngloGold Ashanti selected the high pressure comminution process for their Tropicana Gold Mine in Western Australia. The project was developed by AngloGold Ashanti with the support of Lycopodium Engineering, Perth. Maschinenfabrik Köppern – Germany designed, manufactured and supplied the HPGR. The mine was commissioned during October 2013 and reached full operational capacity within 6 months. This case study describes the challenges faced during the project design stages and first years of operation of the HPGR at the TGM mine site. Pilot plant scale test work summary and HPGR size selection is compared with actual operation results. In summary, the HPGR reached full operational capability within days of commissioning. This operational availability of the HPGR contributed to a quick ramp up of the entire plant that was achieved within weeks of commissioning. By February 2015 the HPGR had reached over 10,000 on load hours in service. The HPGR’s high mechanical availability and excellent performance of studded wear protection were the primary contributing factors for the HPGR success.

PL

Proces wysokociśnieniowego rozdrabniania rudy w prasach walcowych (proces HPGR) został wybrany przez AngloGold Ashanti Australia dla ich najnowszej kopalni złota Tropicana (TGM) w Zachodniej Australii. Tropicana została zaprojektowana przez AngloGold Ashanti przy wsparciu Lycopodium Egineering, Perth. Niemiecka firma Maschinenfabrik Köppern wyprodukowała i dostarczyła HPGR. Kopalnia Tropicana została uruchomiona w październiku 2013 roku i osiągnęła pełną zdolność operacyjną w ciągu 6 miesięcy. Poniższy artykuł opisuje trudności i sukcesy w czasie poszczególnych etapów rozwoju projektu od testów pilotażowych do wyników produkcyjnych w pierwszych latach przeróbki rudy. Referat opisuje jedynie wyniki osiągnięte z HPGR. Podsumowując, HPGR osiągnęła pełną zdolność operacyjną w ciągu kilku dni od uruchomienia. Ta gotowość operacyjna HPGR przyczyniła się do szybkiego rozruchu całego zakładu przeróbki rud. Do lutego 2015 r HPGR przepracowała ponad 10,000 godzin. Wysoka dostępność mechaniczna HPGR, świetne wy-niki produkcyjne i długotrwała żywotność wykładzin walców były głównymi czynnikami, które przyczyniły się do sukcesu HPGR.

8

Ocena efektów uzyskanych w procesie rozdrabniania surowców mineralnych w wysokociśnieniowej prasie walcowej

Surowiec-Kruszec K., Saramak D.

Kruszywa : produkcja - transport - zastosowanie

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2014

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Nr 3

44--46

PL

Podstawą procesu przeróbki mechanicznej surowców mineralnych są operacje rozdrabniania i klasyfikacji. Determinują one jakość produktów końcowych (w przypadku produkcji kruszyw grubo i drobno uziarnionych) lub efektywność operacji wzbogacania metodami fizycznymi, chemicznymi lub innymi (dla przeróbki rud).

9

Mathematical models of particle size distribution in simulation analysis of high-pressure grinding roll operations

Saramak D.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 1

121--131

EN

The high-pressure grinding roll (HPGR) technology is currently one of the most efficient methods of hard ore comminution from the scope of the energy consumption. Throughput and energetic models of performance are quite well developed, but technological models predicting the comminution effects still needs an in-depth research. In the paper author presents the method of modeling of HPGR products’ particle size distribution by using suitable mathematical models. A basis of the HPGR perfor-mance assessment and HPGR-based crushing circuits design is a product’s particle size distribution. In order to precisely determine the particle size distribution of a HPGR product, parameters of product’s particle size distributions should be conditional on the main technical parameters of the roller press like operating pressure and the speed of rolls. The most accurate approximation of a distribution of size parti-cle appears to be Weibull’s truncated distribution and it is possible to obtain significant relationships between the approximation formula and the value of operating pressure, or feed characteristics. It makes possible a determination of mass recoveries of the product’s respective size fractions and the productivity planning. Instead of pressure, the other HPGR operating parameters can be applied, but the pressure value appears to produce the most relevant relationship. A determination of HPGR product’s particle size dis-tribution is a basis of the press operation simulation analysis.

10

Determination of the nip zone angle in high-pressure grinding rolls

Saramak D., Naziemiec Z.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 1

243--253

EN

A proposal of the nip zone angle determination in high-pressure grinding rolls (HPGR) crush-ing process is presented in the paper. Knowledge of the nip zone angle value makes it possible to deter-mine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll’s geometry and the change of the HPGR chamber’s volume together with the roll rotation, while the second one considers the outlet gap width. Results of the nip zone angle calculations according to both methods are similar and show that the nip zone angle is around 3o. The verification was carried out in a piston-die press and experimental results show that the product size distributions from HPGR and piston-die press are similar. The methodology of the nip zone angle determination presented in the paper has then its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization.

11

Główne aspekty rozdrabniania twardych surowców mineralnych w wysokociśnieniowych prasach walcowych

Gawenda T.

Górnictwo i Geoinżynieria

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2009

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R. 33, z. 4

89-100

PL

Wysokociśnieniowe prasy walcowe (HPGR) trzeciej generacji to jedne z najbardziej nowoczesnych maszyn i coraz częściej stosowanych w nowo projektowanych zakładach przeróbki na świecie. Również podczas modernizacji zakładów zastępują one miejsce starych kruszarek pracujących we wtórnych stadiach rozdrabniania i młynów w pierwszych stadiach mielenia, dając znakomite korzyści w postaci oszczędności energii elektrycznej, mniejszych kosztów eksploatacji i wysokiej jakości produktów. W niektórych przypadkach prasy całkowicie zastępują młyny, zarówno przy produkcji mączek mineralnych, jak i rud kierowanych do wzbogacania. W artykule (we wstępie) przedstawiono główne problemy związane z eksploatacją starszych typów pras oraz znaczenie i wykorzystanie nowych pras. W drugim rozdziale omówiono budowę, zasadę działania i przebieg procesów rozdrabniania w HPGR, a w rozdziale trzecim przedstawiono korzyści wynikające z zastosowania pras na przykładzie konkretnych układów technologicznych.

EN

The high pressure grinding rolls (HPGR) of third generation are ones of the most modern devices and are often applied in new designed mineral processing plants in the whole world. Furthermore, they replace older crushers working on secondary comminution stages and mills on first grinding stages, being the source of high profits, mainly by energy savings, lower exploitation costs and higher quality of products. Sometimes, they totally replace mills, both by production of mineral flours and ores directed to beneficiation process. In the introduction to the main part of the paper, the main problems relied to exploitation of older grinding rolls types, as well the signification and application of the new ones were presented. The second chapter contains the discussion over the construction, rule of working and course of the comminution process in HPGR and the third one shows the benefits occurring from their applications on the basis of certain technological systems.

12

Analiza zmian obciążenia materiału w strefie zgniotu pras walcowych

Naziemiec Z., Saramak D.

Górnictwo i Geoinżynieria

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2009

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R. 33, z. 4

221-234

PL

Znajomość realnej siły nacisku działającej na materiał w prasie walcowej jest istotna szczególnie z punktu widzenia przemysłu wapienniczego oraz produkcji kruszyw drobnych i kruszyw wypełniających. Zastosowanie zbyt dużych obciążeń w urządzeniu skutkuje niejednokrotnie gorszą jakością produkcji. W artykule podjęto próbę wyznaczenia realnej siły nacisku występującej w prasie walcowej. Zaproponowano dwa podejścia, pierwsze uwzględniające geometryczne zmiany strefy zgniotu oraz drugie związane z wielkością szczeliny wylotowej.

EN

Proper determination of real pressing force in HPGR is especially essential from the viewpoint of lime industry as well as fine and filler aggregates production. Too excessive pressing forces often results in production of lower quality products. Two methods of determination the real pressing force in HPGR were presented in the article. First one takes into consideration geometrical changes in the volume of press's compression zone, while the second is connected with the gap's width.