Paliorema Sulfur Mine and Processing Plant, Milos

Introduction

The ruins of Paliorema Sulfur Mine on the Greek island of Milos are remnants of an important period of industrial history on the island. Milos contains abundant mineral deposits of volcanic origin including sulfur, manganese, bentonite and perlite, all of which were, or continue to be, subject to industrial exploitation. Mining of Sulfur has long ceased to be economical in developed countries since abundant supplies are available as by-products of refining of sulfur-rich hydrocarbons. Pure sulfur is still extracted on a small scale at several volcanic sites such as Kawah Ijen in Indonesia, although this relies on low labor costs and the absence of the need for extraction processes from ores.

In its final years of operation, the sulfur processing plant employed the innovative Svoronos method for highly efficient recovery of sulfur from ore. This method was employed by the Milos sulfur Mines S.A. from 1953 to 1958 when the company went bankrupt following a further drop in sulfur prices. Today the buildings are in a desolate state with most roofs missing, thus exposing the machinery, much of which remained in place, to the elements. Many smaller items have been removed, some to the local mining museum, whilst many others have been stolen as access to the site is not restricted.

Ruins of Svoronos process sulfur-processing plant (2012)	Sulfur-processing plant viewed from beach (2012)	Paliorema Bay with mine buildings (2012)

View from valley with track of powered incline in front of processing buildings (2012)	Manpower-operated tippable minecart for ore transport from mine to processing facilities (2012)

Mine Ownership

Ownership of the Milos sulphur mines, the ruins of which one can see today, passed through a succession of companies, starting in 1862.  Sulfur mining had been taking place in a relatively unregulated manner at various sites on Milos before this date, yet these earlier operations are not subject of this text.  The Greek government first established a legal framework for mining concessions in 1861. The government of King Otto, Greek Monarch from 1832-62, had recognized the potential importance of the sulfur deposits on Milos, in part due to a memorandum by the German geologist Russiger, which suggested setting up smelting operations for sulfur on Milos, based on methods deployed in the Naples sulfur mine. In 1850, the government sent Mineralogist P. Vougioukas to Milos, to assess the most beneficial way of exploiting the sulfur deposits. Since the state was short on capital, it was decided to allow exploitation by entrepreneurs who would pay the state for mining concessions.

The first Greek mining concession of any kind was issued to the London-based Greek capitalist Vassilios Melas on 11.05.1862, initially for the whole of Milos, later reduced on request by Melas to a large (14423 stremmata (about 14.4 square kilometers)) area in eastern Milos covering 10 mining sites, most notably Firligos, Fyriplaka, Kastanas and of course Paliorema (often just referred to as Remma, but herein referred to as Paliorema to distinguish from the next bay north of Paliorema which is generally referred to as Rema and was a site notable for Millstone Mining (see "Mines in the Aegean - Industrial Archaelogy in Greece" (Nikos Belavilas) for details).

Sulphur was extracted the following year at Firligos at the base of coastal cliffs about 2 km south of Paliorema. Unregulated activity had already taken place at Firligos starting as early as the 1830s. About 125000 GRD were invested in the construction of three furnaces at this site (Note: Because multiple mine sites operated under a single company there is sometimes ambiguity as to the location and timing of construction activity or sources of the products).

From 1856-1874, 80000 tons of pulverised sulfur earth (8-15% S) were sold for viticulture. Underground mining began in 1862, with 64000 tons of ore extracted by 1871. By the middle of the 1870s, sulfur earth was obtained from Tsakistra and Fyriplaka, whilst sulfur was being extracted at Firligos and Kastanas, using three furnaces at Firligos and one at Kastanas, and also at the increasingly important Paliorema site where sulfur was initially obtained from poor sulfur ores using four Calcaroni kilns and subsequently from richer ores using cast-iron Doppioni kilns. Even after construction of the Doppioni kilns, total pure sulfur output reached only about 6000 tons per year, far short of the amount needed for viticulture in Greece alone. Poor yields were partially a result of the high percentage of silica in the tuffaceous ore, which hindered efficient sulfur separation.

The mine was sold to Michael and Victor Melas in 1877, following which 150000 GRD were invested in construction of a pier, roads, laboratories, warehouses and "recreation facilities".  The mine was then sold in 1880 to the Municipal and Public Works Co. S.A. (Α.Ε. Δημοσίων και Δημοτικών Εργων), with major shareholders being the General Credit Bank, M. Melas, T. Moutzopoulos and A. Moutzopoulos. The mine was at is most productive during this period, with 15000 tons of ore being extracted and processed in 1891 (In the total period from 1871-1904, it is reported that 227500 tons of ore and 45500 tons of pure sulfur were obtained (Gounaris via Belavilas); the accuracy of these figures is however questionable as it would represent a 20% yield from ore with up to 20% sulfur, which was clearly not possible with the methods used). Following the collapse of General Credit in 1893, the company entered a difficult financial period. In 1898, the sulfur mining rights were passed to the General Contracting Company (Γενική Εταιρεία Εργοληψιών) which merged into the Municipal and Public Works Co. S.A. in 1906. It is noted that the mines were not being operated in 1904-1910 due to a decline in sulfur prices due to oversupply following development of the Frasch process in the US. Nevertheless, restructuring continued (as did attempts to render extraction more economical), and in 1909 the Municipal and Public Works Co. S.A. (Εταιρεία Δημοσίων και Δημοτικών Έργων) merged with the "Hellenic Mining Company" (Ελληνική Εταιρεία Μεταλλείων) and the "Boeotia Mining Company" (Μεταλλευτική Εταιρεία Βοιωτία) creating the Mines and Public Works Co. S.A. (Α.Ε. Μεταλλείων και Δημοσίων Εργων), which was in turn absorbed into Greek Enterprises S.A. (Α.Ε. Επιχειρήσεων εν Ελλάδι) in 1913, during another period (1912-1917), when essentially no mining activity was taking place.

Documents relating to transfer of ownership in 1913 (Land Registry of Milos, Vol.46, Deed No.177 / 09.04.1913), still show significant inventory at the Firligos site, including 8 Gill system kilns, 6 Doppioni system kilns, a sulfur mill, coal and sulfur warehouses, three boats, a quay and pier, mine railway. It is not clear whether the site was reopened when operations at the mines resumed in 1918, certainly the main literature sources on the sulfur mines make no further mention of it. Over time, mining activities seem to have been largely abandoned at all sites except Paliorema, although apparently a small number of miners were deployed at Kastanas, on the coast about 5 km north of Paliorema, in the 1950s.

In 1921, the mining operations were acquired by Alexiou, Antonakopoulos & Co. (Π. Αλεξίου, Ν. Αντωνακόπουλος και Σία), which in 1928, together with Greek Enterprises S.A., established the final company that actively extracted Sulphur in Milos, the Milos Sulphur Mines S.A. (Θειωρυχεία Μήλου Α.E.).

Greek Enterprises S.A. initially held 30370 shares, whilst Alexiou, Antonakopoulos & Co. held 19621. Capital was increased from 5,000,000 to 6,500,000 GRD in 1930 to accommodate an investment by the "International Mining and Ore Trading Corporation SA.". The mines however remained unprofitable (for the entire period of 1929-1940) and suffered partial closure and labour disputes during the early 1930s. As a result, and to finance the complex Svoronos sulfur processing plant and associated infrastructure at Paliorema (which cost an estimated 20,000,000 GRD) the share capital was increased several times, at least in 1930, 1934, 1938, 1939 and 1941 (the images of share certificates below show shares issued during the latter two capital increases).

Operations were again interrupted between 1946 and 1952, after which they resumed under new management for a period of about 6 years (with a brief closure in 1956 after another dispute between the mine and the Agricultural Bank) until final closure in July 1958 and official bankruptcy on September 13 that year. Whilst the mine has passed into several further hands since 1958, mining activity was merely sporadic and of an exploratory nature (although 2155 tons of ore were extracted by S&B Industrial Minerals S.A. in 1980, 943 in 1983 and 932 in 1986 to maintain mining rights, which eventually lapse if no mining activity takes place). Sulfur prices never justified a resumption of operations, even though significant sulfur and underlying alunite (hydroxylated aluminium potassium phosphate which can be used for producing potash or alumina) deposits had been located between 1966 and 1969 during exploratory work overseen by J. Svoronos, employed as Director by Eleusis Bauxite Mines S.A., which owned the mine at the time.

The following images show share certificates of the Milos Sulphur Mines S.A. company with some of the associated dividend coupons attached at the bottom. Certificates of 100 shares were also issued, at least in 1942. If you have other share certificates from this company or any of the earlier owners, please contact me so that images thereof can be added to the website.

Milos Sulphur Mines S.A. - 1 Ordinary Share	Milos Sulphur Mines S.A. - 5 Ordinary Shares	Milos Sulphur Mines S.A. - 25 Ordinary Shares

Milos Sulphur Mines S.A. Share Certificate for 1 Preference Share	Milos Sulphur Mines S.A. Share Certificate for 5 Preference Shares	Milos Sulphur Mines S.A. Share Certificate for 25 Preference Shares

Site Layout

Maps are available showing the layout of the Paliorema mine (Milos sulfur Mines, Grigoris Belivanakes, ISBN 960-91562-2-3; Annexes). The main sulfur bodies from which ore was extracted were located underground and accessed by horizontally driven adits. The mine adits contained narrow-gauge rails on which minecarts were moved by hand. The rails further connected the mine adits to the main processing facilities and also to the dock facilities for loading the sulfur onto boats. One tunnel (now blocked) extended south from the current site of the administration buildings and connected to possibly the first underground deposit mined in the valley, since an early ore mill was originally found at its exit. The tunnel extended to a small dock in Siskinos bay, south of Paliorema, allowing supplies from small boats to reach the mine during strong northerly wind conditions that prevented use of the main dock facility. The main bodies of sulfur mined were located in the hillsides flanking the Paliorema valley several hundred meters inland (west) of the main mine buildings and were linked to the processing plant area by the main No.1 (or "Ace") adit. During the 1920s, Adit No.2 also appears to have been a main access point to the mine since a twin-railed incline was in place to lower mine carts from the level of adit no.2 to the floor of the valley where the ore was processed.

Historical photo showing layout of sulfur kilns, rail tracks and mine entrances in 1923 (Source: ETH Zürich (Photographer: Immanuel Friedlaender (1871-1948)). Adit no.1 is presumably located directly below the top of the incline, which leads up to the level of adit no.2 and/or the valley behind (if the valley floor was higher at the time).

Todays mine buildings largely result from a period of construction starting in the 1930s, when a major modernization program was implemented, including the construction of the main hill-side sulfur processing plant which forms the most prominent part of the ruins today. The plant has a twin-railed sloped incline for transporting ore from a storage bunker at its base to the top of the processing facility. From here the ore was passed through the processing facility and was crushed before sulfur was extracted by heating followed by separation by sieving and flotation processes, as shall be explained in more detail in the following section. Further auxiliary buildings housing offices, accommodation, laboratories, workshops and the generator were constructed during this period. A small stone bridge connected the processing plant to a dock. The dock had a derrick crane for lifting sacks of sulfur onto waiting ships, The dock area also housed the pumping station, that pumped seawater to large storage tanks above the mines buildings. A metal bridge connected the auxiliary buildings to the processing facility at the height of the construction bureau.

Paliorema valley with mine and processing facilities viewed from hillside above dock facilities (2012)	Processing plant (2012)	View towards processing plant from remains of dock facility (2012)

Paliorema valley with mine and processing facilities. Entrance to Adit No.2 is above the left-most buildings at end of upper terrace extending from left of incline (2026)	View of Paliorema with approach road. Normal 2WD cars will struggle to reach the bend and can not proceed further to the beach due to poor road conditions (2026)

View from valley with track of powered incline in front of processing buildings. Road bends around remnants of old sulfur kilns (2012)	View from valley. Note the terrace leading to the middle of the incline. This extends inland to Adit No.2 and was present before the processing plant was built. Its role, if any, in later years of mine operation is not known (2012)

Sulfur Processing Plant (Svoronos Method)

At Paliorema, sulfur ore was not only mined but also processed before relatively pure sulfur was shipped from the site. Initially, sulfur was extracted from crushed ore by heating the latter in a set of kilns. In the kiln, the sulfur was melted and a portion of it would manage to flow to the bottom of the kiln where it could be collected. However more than half of the sulfur was lost due to combustion. Various forms of this process were used at Firligos and Paliorema, progressing from the Calcarone process to the Doppioni, and finally Gatto-Gill process (although the 1957 Krupp Report (established when Krupp was considering a joint venture with the mining company) suggests that the Calcarone process was still being used in 1939). The Calcarone process generally involves a large kiln with a sloping base with a grid at the lower side. After igniting the sulfur, the top of the kiln was covered with slag, thus reducing access of oxygen and reducing combustion. As the sulfur burns, a proportion melts and drains to the bottom of the kiln. Pollution is significant, yet reduced to some extent compared to the most basic open-topped oven types (Calcarella (probably not used at the mine)), but the process takes 1-3 months (depending on oven size).

The Doppioni process involves the use of two connected chambers. One vessel is generally heated using e.g. wood or coke and this causes melting and finally (above 410'C) evaporation of sulfur. The sulfur gas passes through a pipe into the second chamber in which it cools and condenses, allowing it to be collected in relatively pure form. The basic principle of cooling sulfurous gases to achieve condensation can be seen in a simple form today at Kawah Ijen sulfur mine, where fumarolic gases are cooled in pipes with liquid sulfur being collected at the bottom of them.

In the Gatto-Gill process, which has the advantage of relying on sulfur combustion for heat generation (saving costs for wood and coal when these are expensive or difficult to source) a series of chambers is used with the exhaust gases flowing to adjacent chambers which are thereby preheated and finally catch fire. The process is similar to the Calcarone process insofar as sulfur is collected at the base of the kiln, which again has a sloping base, yet gases from sulfur combustion are used, rather than being directly released into the environment. The kilns are smaller and the process has the huge advantage that it can run continuously when an array of kilns is used with staggered loading and operation.

Even employing the Gatto-Gill process, recovery of only about 35% of the sulfur within the ore at Paliorema could be achieved, compared to 65% in sicilian deposits using the same method (Ekonomopoulos, 1952, Ind. Engineer. Chem. 44(1), p.105-106). This was a result of the properties of the locally mined tuffaceous ore which tends to break down in the smelters once the sulfur is fluidized and thus obstructs passage of sulfur to the base of the kiln. Further, the process also results in the release of noxious sulfurous gases, particularly sulfur dioxide. These had a debilitating effect on the early miners at Paliorema with many dying of lung conditions, in particular consumption (pulmonary tuberculosis).

A number of engineers employed by the mines attempted to achieve improved yields. For example, E. Schmatolla (1906-1907) and A. Skintzopoulos (1909-1910) tried to apply a method initially developed in Sicily, wherein sulfur earth was mixed with water and lime to form briquettes which were more easy to smelt. The new method, and kiln adapted thereto, were however unable to render operations economical and mining operations were again essentially paused from 1912-1917. The method was however reused, in particular for processing of fine ores, when mine development accelerated in the period from 1932-1934, at a a time where the Paliorema site also received 2 new furnaces and a new mill for pulverization of sulfur earths. Washing methods for enriching fine ore were also assessed.

The processing plant which lies in ruins today was constructed in the 1930s and started to produce small amounts of sulfur from 1935-1940 before disruption by the war. It is not clear whether problems with the process prevented a further ramp-up in production. With the help of a loan from the Agricultural Bank (ATE), operation of the processing plant was resumed (possibly after some technical modifications) in 1953 (with a brief interruption following a fatal boiler explosion on May 21st, 1953) and the plant continued to operate until 1958, producing about 15000 Tonnes of Sulfur (about 99.5% purity) in this period for the Agricultural Bank, which had been effectively granted a state monopoly for sulfur and supplied agricultural collectives. The plant was constructed for processing sulfur-containing ore by the Svoronos process.

In 1927, the greek inventor Jason J. Svoronos applied for a greek national patent (GR1560) for a novel form of sulfur extraction from ore. An equivalent patent was applied for in germany in 1937 (DE703159). The process no longer relies on combustion of sulfur and yields as much as 90% of the sulfur entrapped in ores. In the process, the sulfur-containing ore is crushed and then basically heated in a solution at a temperature of about 120'C. The sulfur melts at this temperature and upon cooling, small lumps of sulfur form which can be separated by a flotation process. Looking at the mine layout at Paliorema (based on technical diagram of Hungarian Stefka (Annex 6 in "Milos Sulfur Mines")), it is however evident that 2 heating steps were employed, at least at some stage during the facilities operation. This is in line with the teachings of a slightly more recent patent by Svoronos (DE864232, patented 27.07.1938; Based on greek patent applications filed on 26.07.1937 and 22.01.1938).

DE864232 explains the process in some detail. In a first step, the ore is ground to the size of a hazelnut and then loaded into a pressure cooker, in which it is heated to a temperature of at least 120'C for a time sufficient to melt the sulfur in the ore (the cooker may alternatively contain a solution that doesn't boil until at above 120'C at atmospheric pressure, in which case the vessel would not need to be pressurized). During heating, the mixture is agitated to further break up the ore and to allow the molten sulfur to start to form small globules (granule size can be influenced by speed of agitation). The mixture is then allowed to cool, whilst agitation continues. This ensures that the sulfur globules remain small and solidify to granules with a diameter of less than 1 mm. The material is sieved to remove any rock fragments over 1 mm in size. At the end of this first step, one thus obtains a mixture of sulfur granules and small fragments of the tuffaceous rock in which the sulfur was embedded.

In the second step, the sulfur must be removed from the fine rock fragments. The mixture from step 1 is again heated in a pressure cooker to melt the sulfur, this time with gentle or no agitation. In the presence of higher sulfur concentrations and without significant agitation, molten sulfur forms larger globules. After cooling, one obtains a mixture wherein the rock fragments remain at or below the cut-off size of the sieving process at the end of stage 1 (e.g. less than 1 mm), whilst the sulfur granules are now significantly larger. A further sieving step can now be employed, wherein the sulfur is retained by the sieve and the small rock fragments pass through it and are thus removed. Alternatively to step 2, a flotation-separation process is suggested (as in the earlier patent).

The process initially employed in the processing plant at Paliorema was presumably based on the above patent, yet based on documents from the German Krupp company, which visited the mine shortly before its closure and documented the process (and allegedly obtained "global rights" for the process in 1956), some modifications appear to have been in place. In particular, on the diagram of the plant (Stefka) it appears that whilst two sequential heating steps are employed, each followed by sieving steps, the second sieving step is followed by a flotation step (i.e. the two alternatives for step 2 in the DE864232 patent appear to have been combined to achieve improved purification).

The text of the Krupp report however suggests that a single pressure cooker was used, which is consistent with the machinery embedded in the ruins today. The Krupp report describes the process in detail (note: translated from german):

The crude ore (currently 80-100 t/day with a content of 15-20% S) is initially pre-crushed in a crusher to 100 mm. If necessary, it undergoes further crushing in a second crusher to 20 mm and is subsequently channeled into 2 silos. From there, the crushed product ends up in a vessel with a capacity of 3.1 t, which is positioned before the autoclave and used for loading the autoclave, which is of the same capacity. In the autoclave, which rotates at 7 revolutions per minute, the product undergoes processing for one minute under a pressure of 7 atm with hot water, and subsequently for 10-45 minutes with steam. At a temperature of 135°C to 140°C, the sulfur melts and is released from the host rock. Then, cold water under pressure (7 atm) is channeled in for 1-1.5 minutes; in this manner, and at a temperature of 80°C, the molten sulfur cools and forms into pellets. After the product is discharged into a stone receiving basin and further cooled with cold water, the product is classified via a simple screen of 12.5 mm. The coarse product poor in sulfur is discarded into the waste piles as barren material. The fine fraction, consisting of gravel, mud, and sulfur, passes via a receiver into a thickener. After overflowing, the clay is removed. The product containing sulfur is enriched through the batch-operated flotation method in 4 cells into a concentrate with a content of approximately 90% S. The oil (petrol) consumption per ton of sulfur concentrate amounts to 10 kg. After cleaning and water removal, the sulfur product is channeled into a dissolution autoclave (2 t). Filled with steam at a pressure of 6 atm and with intermittent discharging, pure sulfur is produced. Cooling takes place in an open concrete tank. Until the spring of 1957, the solidified sulfur was ground in a mill at 350 mesh (feed 92%) with a daily production of 15 t. Recently, 2 centrifugal ball mills of Italian construction have been installed, with an output of 12 t daily each. The recovery efficiency of sulfur is approximately 87%. The 13% losses are distributed as: 4% S in the coarse fraction (+12.5 mm), 5% S contained in the mud, 2% loss during flotation, and approximately 2% S losses during dissolution. During each shift, the processing plant employed 5 people for pre-processing up to feeding the autoclave, 2 people for operating the autoclave, 7 people for the flotation process and 2 people for the dissolution/melting autoclave.

The plan of the plant (according to Stefka) and a greek translation of the text of the Krupp Report are found in the book "Milos sulfur Mines" (ISBN 960-91562-2-3). Certainly, the 1st pressure cooker is today missing from the plant (as is essentially all machinery numbered 10-13 in the plant layout shown below). Given its size, the pressure cooker must have been removed by the mine owners. 

The processing equipment was originally arranged in the plant as follows (based on Stefka Annex):

After being transported up the incline, the ore passed through a sorting and crushing process in the rooms nearest the incline, was then elevated to the top of the middle row of rooms in which it was heated to extract sulfur and again subjected to size-sorting processes, following which it was lifted by conveyor belt to a silo above the final set of rooms containing a second heating apparatus for further separation of sulfur from the rock followed by size-sorting / flotation-separation to isolate the sulfur. Further buildings located on the valley floor below the main plant were for storage, further refining (dissolution) or milling steps. The two Gilardoni centrifugal hammer-mills were for powdering the product before packaging for shipping and were only installed in 1957, shortly before closure of the plant. During the war, milling was performed in Adamas on the premises of the "Mining and Chemical Enterprises Co. Ltd.".

Sulfur kilns used prior to construction of Svoronos Plant (2012)	Sulfur crystals embedded in tuffaceous material (sulfur ore), Paliorema. (Average Sulfur content is about 15-20%)	Sulfur kilns used prior to construction of Svoronos Plant (2012)

Remains of winch of smaller incline allowing lowering of carts to level of workshops (2012)	Remains of storage bunker at base of main powered incline (2012)	View up twin-tracks of main powered incline. Used to move ore from bunker to processing facility (2012)

Large funnel-shaped storage bunker for capturing ore tipped out of wagons at top of sloped incline (2012)	Swinging transport band and vibration sieve for first separation of ore by size prior to crushing step 1 (2012)	Elevator for transporting crushed ore to silo above first rotating boiler (2012)

Top of elevator (2012)	Elevator (2012)	Former silo at top of elevator. Rusting bedframes suggest some workers slept there (2012)

Silo for storing material after processing in 1st rotating boiler (2012)	Location of rotating sieve (no longer present) for sorting material after processing in 1st rotating boiler (2012)	"Mixer" (exact function unknown) at base of conveyor belt taking material to silo above second rotating boiler (2012)

Conveyor belt taking material to silo of 2nd rotating boiler. Part of chimney lies on track (2012)	Top of conveyor belt taking material to silo above 2nd rotating boiler (2012)	Rails leading from silo at top of conveyor belt (Function unknown, possible that delivered crushed ore while bypassing machinery relating to and including 1st rotating boiler) (2012)

Main boiler room. Used for generating heat for processing boilers and autoclave. Note, upper section of chimney lying on conveyor belt  (2012)	Remaining bottom section of chimney (2012)	Oil-burner powering main boiler (2012)

Core part of Svoronos processing plant: 2nd rotating boiler (out of view at middle left of image) and sieving / flotation machinery (2012)	Opening of storage silo above 2nd rotating boiler (2012)	Rotating boiler driven by 10 hp motor. Top right is funnel for loading (and measuring load) (2012)

Storage bunker above sieving / flotation machinery (2012)	Sieving / flotation machinery for separation of sulfur from remaining rock fragments (2012)	Base of sieving / flotation machinery (2012)

More detailed look at critical 2nd stage rotating boiler (2012)	Railtrack leading out of final room of main processing plant building, presumably for removing waste material (2012)

Refining autoclave in building adjacent to main processing plant complex (2012)	Unknown sulfur refining machinery (maybe hopper associated with the pan grinders) at base of hillside processing plant (2012)	Gilardoni centrifugal hammer-mills (For breaking sulfur clumps into powder form) (2012)

Fuel storage tanks in room with refining autoclave at base of processing plant (2012)	Gilardoni centrifugal hammer-mill (2012)	Processing plant with metal bridge and small constructors bureau in foreground (2012)

Seawater storage tank above processing plant (2026). The tank originally had a panel with a dial indicating the water level attached between the two supports.	Support for piping through which seawater was pumped to water reservoir above sulfur-processing plant (2012)	Seawater storage tank above processing plant (2026)

Workshops and Generator Building

On the southern side of the Paliorema valley is a row of five auxiliary buildings. Nearest the sea is the largest concrete building, the combined office / accommodation block. Moving inland one sees three buildings, (1) the shop and storage, (2) the generator building and (3) workshops with blacksmith and carpentry facilities.  Furthest inland is a workers accommodation block. According to an "employment report" from 20.04.1954 (p.148 of "Milos Sulfur Mines"), the mine employed about 15 administration and service staff, 32 repairs / maintenance staff (of which 9 in engine room and 15 in the workshops). 19 workers were employed building the road, 9 for transport, 70 in the processing plant and about 100 in the Paliorema mine. Interestingly, there is also mention of 27 miners at Kastanas, further north along the coast.

According to the 1957 Krupp report, installations at Paliorema were powered by 3 electric generators (2 M.A.N. and 1 Fairbanks-Morse, with a combined 700 horse-power. 2 Mobile generators (DEMAG, Arpick) and a stationary compressor (Flottmann) with a combined 140 hp were used to generate compressed air (required at 6 atm for the pneumatic drills) .

View to auxiliary buildings from top of powered incline of processing plant (2012)	View over processing plant to workshops, offices and accommodation (2026)

Abandoned store (2012)	Abandoned store (2026)

Seawater storage tank above workshops / generator building (2026)	Pipe supplying seawater to workshops / generator building (2026)

Main M.A.N. diesel generator for mine / processing plant (second M.A.N. generator is no longer on site) (2012)	M.A.N. generator in 2026	Former location of further generator

	Machinery with unknown function in generator building (2026)

Metal workshop and caged tools store (2026)	Mobile generator / compressor (?) for driving mine machinery parked outside generator building (2012)	Tools store, winches, ventilation fan in metal workshop (2012)

View from metal workshop to door to blacksmiths (2026)	Blacksmiths with view to doors to metal workshop and generator room in distance (2026)	Blacksmiths with winch (2026)

Winch in blacksmiths. Note that it had been brought in, presumably for repair, on small rail wagon (2026)	Abandoned storeroom to west of blacksmiths in same building (2026)

Accommodation & Office Block

The mine lies a distance from the nearest villages, so miners generally remained at the site overnight. In the early days of the mine, miners often slept in tiny caves, in the late 1930s, concrete accommodation blocks were constructed. Apparently, the miners would have been preferred to be transported by bus to their home villages (not possible due to the lack of a proper road until 1953), the company however wanted them to remain on site.

The block nearest to the sea also had offices and a simple shop / canteen where food could be purchased using tokens. These tokens were generally issued in place of part of the salary, sometimes almost completely replacing it when the mine was short of cash. Aluminium tokens of 50 lepta, 1, 2, 5 and 10 drachmen were issued with a design including the Milos Sulphur Mine name and symbol. Simple 2 (copper) and 5 (aluminium) lepta tokens, with the number 2 or 5 thereon, but no further text or other features, were also used.

Tokens for purchasing food and drinks from the mine canteen (Text: Milos Sulphur Mines A.E. - Headquarters in Athens)

	Accommodation / Office Building (2012)

	Inside second floor of accommodation (2012 (except right image, 2026))

	Workers accommodation inside first floor of seaside accommodation/admin. block  (2026/2026/2012)

Inside 2nd floor of accommodation (2026)	Mine managers office	Inside 2nd floor of accommodation (2026)

View of back of office / accommodation block including terraces	Toilet outside accommodation block (2026)	View of back of office / accommodation block with stairs up to managers office

Food store was located in top left corner of building with corrugated iron roof.	Office / accommodation with bridge to dock. Building at far right with largely missing iron roof was site of food store (2026)	List of food items obtainable from store, including olives, bread, cheese and beans. Image of board displayed in Milos Mining Museum.

Workers Accommodation

For most of the years of operation of the sulfur mine, workers slept in simple caves and scattered small stone buildings in the vicinity of the mine. The caves were often carved out of the rock and walled up at the front. Nearly all had heating / cooking niches with little gaps for the smoke to escape near the door.

Simple workers accommodation near adit No.5 (2026)	Inside workers accommodation near adit No.5 (2026)	Workers cave dwelling on valley floor

Workers accommodation block built during main construction period starting in 1930s (2012)

Finally, during the major period of construction starting in the 1930s, a dedicated accommodation block was constructed (in addition to the accommodation in the multipurpose accommodation and office block shown earlier). At this time a food shop (see list of food in previous section), and possibly also canteen was provided for the large numbers of workers on site. This was located in the storage building next to the main office / accommodation block. It is noted that most rooms had a small cooking niche, suggesting that workers largely prepared their own food. In spite of these improvements accommodation was cramped and insufficient, even in the 1950s.

Accommodation block (2026)	Stairs to 1st floor accommodation block (2026)	Lockers and washing area, 1st floor accommodation block (2026)

	Rooms with old bedframes, 1st floor accommodation block (2026)

Ground floor room, accommodation block (2026)	Foldable bedframe (2026)

Dock Facilities

The processing plant was connected by a single rail track to the main dock facility where sulfur was shipped out of Paliorema. The dock area had a loading crane, a tunnel (see section below), and a pumping station for pumping seawater along a series of pipes to the large storage tanks above processing plant and workshops. The crane, and much of the platform is was on, has collapsed into the sea. The dock was the main means of access to the site, with the gravel road only developed starting in 1953. Only a simple track led to nearby villages before the road was built.

View from above processing plant. Dock facility at top left corner of image (2012)	Stone bridge with rails for transporting sulfur from processing plant to dock facility (2012). In the final years of operation ore was transported by lorry to Adamas port.	Rails leading to dock (2012)

View to dock area (2012). Foreground: support and pipes of water supply to tank above processing facility. Middle: dock for small boats with remains of pump station above it in image. Remains of main dock where crane was located on left, tilting towards water.	Remains of main dock where crane was located in 2012. By 2026, the block on the right had also collapsed into the sea	Support / pipes of water system leading up to storage tank above the processing plant (2026)

Dock and pumping station area (2026). Walls of pumping station still standing in 2012 have now collapsed	Dock with anchoring points for crane (2026)	View from dock towards mine (2026)

The 1957 Krupp report discloses that 2 electric pumps with a capacity of 100 cubic meters per hour were used for pumping to a height of 70m (main water tank above processing plant). A further pump with a capacity of 20 cubic meters per hour could pump water to a height of 20m (tank above workshops). The sulfur purification process used significant amounts of water. The pumps no longer appear to be on site.

Floor of pumping station at dock (2026)	Collapsed pumping station at dock (2026)	Probable component of pumping system for saltwater supply to storage tanks (2026)

Seawater pumping station at dock (2012)	Seawater pumping station at dock (2012)	End of pipe for drawing saltwater into pumping system (2012)

Broken anchoring point of crane (2026)	Remains of rail track connecting dock to processing plant (2026)	Dock for small boats (2026)

	Remains of derrick crane lying underwater (2026)

	Remains of derrick crane lying underwater (2026)

Mine Entrances & Tunnels / Adits

The hillsides flanking the upper Paliorema valley contain numerous adits accessing the underground sulfur deposits. The primary adit in the Paliorema valley in the last years of operation was no.1 ("Ace") adit. This connected the main sulfur bodies to the valley floor near the processing plant. Unfortunately, the adit and adjacent storehouse have been buried by a landslide. Adits can also still be seen at Firligos.

Map showing approximate location of main underground workings (based on maps from 1936 (Dock Tunnel), 1957 (all other tunnels, but N-S tunnel from workshops to Siskinos turned by 30 degrees compared to 1957 map as clearly not accurately placed)) overlaid on google maps satellite data (copyright Airbus / Maxar Techn.). The large most northern ore body was not exhaustively mined due to the mines closure in 1958. Due to the fact that multiple features of the satellite map and underground maps used did not align, the location of adit entrances may be up to 20m from location indicated on map. Many additional adits, galleries and caverns clearly exist. Note: Term adit No.0 is sometimes applied to N-S tunnel connecting workshops to Siskinos bay and sometimes to Dock Tunnel.

Mining was initially performed using simple tools but later pneumatic drills were used, largely for boring holes for the placing of explosives. The explosives were stored away from the main mine buildings for safety reasons. Detonations often ignited the sulfur deposits, with miners reportedly smothering the fires using a form of putty/clay.

Several further adits / tunnels can be found in the vicinity of the dock facilities. The function of a short adit under the rails to the dock is unclear. A longer tunnel adjacent to the location of the crane may have been used for temporarily storing minecarts during ship-loading.

Conditions underground were harsh. Due to residual hydrothermal activity and exothermic reactions occurring as the sulfur-bearing ore was exposed during mine operations, temperatures of over 40'C were reached in one part ("7th floor") of the mine as late as in 1955, when efforts to improve ventilation with further fans had already been made. Miners often worked naked due to the heat. Fumarolic gases and sulfur dust mobilized during drilling operations severely affected the lungs of workers. A number of court cases brought by miners was probably the main motivation behind improvements in ventilation of the mine during its latter years of operation. Mine adit No.2 was used for ventilation and had a large fan installed at its entrance for this purpose. Several further ventilators were in use and compressed air was also pumped into the mine for ventilation purposes, in addition to driving the pneumatic drills.

It is noted that conditions were not only harsh under ground. Medical coverage or insurance in case of death was only established in the later years of operation, and pay was often delayed, partially also due to the Agricultural Bank abusing its monopoly position. On September 10, 1954, 13 workers who had not been paid signed a strike declaration and were immediately dismissed by the mine manager Konstantinos Zannos.

	Various views with arrow showing location of (buried) entrance to main mine entrance, Adit No.1 "Ace" (2026)

Store next to adit No.1 entrance (buried to right of store) crushed by rockfall (2012)

	Portal of adit by dock facility (2012)

Mine entrance at Siskinos bay with remains of small dock (2026)	Tunnel from mine buildings to small dock at Siskinos bay (2026)	Collapsed entrance of tunnel to Siskinos bay (2026)

N side of Paliorema valley opposite mine directors house. Adit No.5 should be at this approximate location, but not clear if it is one of the entrances seen   (2026)	Small accommodation with wooden door and two adits / ventilation tunnels in N side of Paliorema valley opposite mine directors house (2026)	Tunnel in soft white tuff (about 1m high, presumably for ventilation), top right in central image (2026)

Outer entrance to adit No.2 and arch leading towards valley. Note: it is not apparent where a railtrack could have been located in the steep-sided valley so purpose of arch is unknown (2012)	Entrance to adit no. 2. Used for ventilation in the final years of operation. The circular concrete entrance housed a large fan (2012). Why there are two parallel adits is not clear. This could relate to an earlier period where this adit appears to have been used as a main entrance to the mine.

The mine operated in the 1950s using room and pillar (about 30% of volume) mining with backfilling. According to the text of the Krupp report, the mine operated in levels at altitudes of 2, 8, 12 and 19 meters above sea level (It is noted that adit No.2 is at 27m and other mine entrances in the upper valley also appear to be above 19m - it is not clear if these higher levels were no longer in operation and thus not referred to in the Krupp report). The No.1 adit at 10m altitude connects directly to the 2 and 8 meter levels via an inclined shaft. Four fans and ventilation ducts were in operation with temperatures nevertheless reaching up to 42'C at the workface.

Up to 9 pneumatic drills were in operation (Demag, Flottmann) using carbide chisel-shaped tips. Six of these used water from buckets to suppress dust production from the silicaceous pumice. Drill holes tended to be about 1m long. Ammonite was employed as the explosive (with about 2 kg being used per ton of ore obtained). Ammonite is a mixture of ammonium nitrate (80%) and TNT (20%) which detonates at a slower speed than e.g. dynamite, and is thus suitable for fragmenting the soft tuff rocks found in the mine at Paliorema without pulverizing them. 80 tonnes per day of (15-20%) sulfur ore were obtained and loaded manually using rubber baskets into 0.7 ton capacity wagons on a 60 cm gauge track which were pushed out the mine by hand. Unstable adits/galleries were supported by timber obtained from Samos island. Underground operations were arranged in 2 shifts using 4 shift bosses, 9 blasters, 2 loaders, 2 technicians, 8 timbermen, 2 railway track layers, 2 workers for compressed air control and timbering support, and 50 miners with less specialized roles.

Short adit near dock. Roof is supported due to rails passing overhead (2012)

Gas-mask for protection against sulfurous gases, Milos Mining Museum	Ventilator for use in mine, Milos Mining Museum	Mining tools, Milos Mining Museum. Small pneumatic drill is visible.

Mine Directors House

	Ruins of mine directors house perched (in cleaner air) on hill above entrance to valley and view from inside ruins to the processing plant (2026)

Historical Industrial Uses of Sulfur

Sulfur became an increasingly important industrial commodity starting in the late 18th century as it was required for the production of soda ash and sulfuric acid, the demand for which was rapidly increasing as a result of the industrial revolution. The largest supplies of elemental sulfur were obtained from hundreds of Sicilian mines. Sulfur could also be obtained by processing of pyrite (iron (II) disulfide), which was often cheaper. Britain and France were the largest European importers of sulfur and competed for access, with the Sicilian sulfur monopoly granted in 1838 to french company Taix & Aycard having to be revoked in 1846 after Britain threatened to seize Sicilian ships. Prices fell in the mid-19th century as alternative processes for producing soda ash and sulfuric acid were developed. Some additional sulfur demand was generated as a result of the spread of a fungal disease, powdery mildew, in European vineyards. Powdery mildew emerged in Europe in 1845 and in 1854 reduced the french grape crop by 80%. Soon afterwards, it was discovered that growth of the fungus could be controlled by applying sulfur powder. Even though prices remained relatively low, at least 700 small mines (with a total of 30000 workers) were in operation at the end of the 19th century. Sulfur production on Milos was small in comparison to Sicily, yet the Greek considered it important to have an own source. Sulfur production on Milos was never particularly profitable and the mine often struggled to pay wages. Prices were further depressed when the Frasch process was developed in 1895 to cheaply extract sulfur from deposits from brimstone domes in the Gulf of Mexico. The process uses superheated water to mobilize underground sulfur deposits. Today, sulfur is also available cheaply as a by-product the oil refining industry, where sulfur is obtained from hydrogen sulfide gas which is toxic and thus must be degraded to prevent its release into the environment.

Visitor Information

Paliorema mine can be reached by car via a rough unpaved road. Signs in greek to the "Sulfur Mine" (Theorychia) should be followed. Only 4WD vehicles should attempt the last stretch of road. Other vehicles can park at a small loop in the road before it enters the valley (i.e. south of adit No.4 on mine map in section "Mine Entrances & Tunnels / Adits). Alternatively, weather permitting, the mine can be viewed from the sea and small boats can land on the beach.

Many mine buildings are unstable, including floors made of thin and poorly reinforced concrete which may collapse. Hence, entry to buildings is unsafe. Additionally, heavy machinery, roof elements etc. may collapse at any time. Some mine entrances are accessible, but entering the mine is not advisable since the tunnels are unstable and the air quality in the main part of the mine is dangerous, with irritating levels of sulfur dioxide already noticable at some adit entrances. The venomous Milos Viper may be encountered so one should mind where one steps, especially if walking through vegetation in the upper valley. Visitors are asked not to remove any industrial relics from the mining buildings. Indeed it is to be hoped that plans to preserve the site can be implemented before it decays further.

Visitors should combine a visit to Paliorema with a visit to the Milos Mining Museum near the southern exit of Adamantas (= Adamas) town. The museum is sponsored by S&B Mining Corporation, which presently runs much of the mining activities on the island.

Milos also has a number of other geological sites of interest. See main Milos page.

Credits: much of the information on this page was obtained from the extremely well researched book "Sulfur Mines of Milos", written by the late Grigoris Belivanakes. The book incorporates portions of the Krupp report, which Georgios Xydous (who acquired the Paliorema property in 2001) kindly provided to Belivanakes, without which a technical understanding of the sulfur purification processes would not have been possible. Further, detailed information was obtained from "Mines in the Aegean - Industrial Archaelogy in Greece" (Nikos Belavilas, Leda Papastefanaki. Melissa Publishing, Athens 2009), which includes a meticulously researched chapter on mining in Milos (and chapters about many other historical Greek mining operations), which was used for adding numerous details regarding company structure, early processing methodologies and development at the sulfur mines. Nikos Belavilas is thanked for kindly providing a digital copy of the chapter on Milos, which facilitated translation to english.

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