Rectangular Kiln Research Articles

Monte Alban periphery (Oaxaca, middle Mesoamerica): New evidences on the early occupation trough archaeomagnetic study of pottery kilns

Aimed to obtain absolute chronology data for the early stage of Monte Alban, magnetic mineralogy and archaeomagnetic investigation were carried out of recently discovered pottery kilns. Oriented samples belong to four rectangular kilns, both single and double chambers, and one fire pit at the piedmont peripherical area. Susceptibility vs. temperature curves show market thermal instability while large pseudo-single domain grains seem to carry the major part of remanence for the kiln sample. Fire pit samples, in contrast, seem to be dominated by antiferromagnetic hematite. Alternating field demagnetization allowed to reach primary, characteristic magnetization components with reasonably well-defined mean archaeodirections. Possible archaeomagnetic age intervals were obtained considering currently available global models and local curves. The dates are consistent with the most important periods of occupation at the site, although the results may indicate that there was also a significant cultural presence in the Early Classic Period. Recently discovered kilns indicate constant manufacture of pottery. Although we cannot currently define the intensity of production, we believe that pottery could be a specialized activity in peripherical areas of Monte Alban to exchange ceramics or for its local consumption. Consequently, we propose that the piedmont area was an economically autonomous community whose inhabitants dedicated themselves to various tasks throughout their occupation.

Architecture and function of salt-producing kilns from the 8th to 18th century in the coastal Sundarbans mangrove forest, Central Ganges-Brahmaputra Delta, Bangladesh

Subsidence along the central coast of the Ganges-Brahmaputra Delta and a subsequent rapid burial by mangrove mud have preserved a hundred earthen kilns at 11 localities, exposed due to recent coastal erosion. The associated pottery indicates that the kilns were used for salt crystallization in brine pots mounted on perforated hotplates. Four kiln varieties were found at successive elevations. The kiln chamber walls and the basal charcoal layers were dated using thermoluminescence and radiocarbon dating respectively. The oldest kilns with a round outline, found at the lowest elevations, were operating in the early 8th to middle 9th century. Oval-shaped kilns, found at a 1-m higher elevation, were used from the mid-9th to early 10th century. After a 600-year long period without documented kilns, rectangular kilns with a lateral slot were built again at a 1-m higher land surface in the 16th and 17th century. The youngest kiln type consists of rectangular twin chambers dating from the late 16th to mid-18th century and occurs at 1.5 m below the present sediment surface. Architecture and functioning of these rectangular kilns are reconstructed, showing a multi-step procedure. This technique had been improved in the 19th century when pyramidal kilns were described in historic records.

UBC Excavations of the Roman Villa at Gerace, Sicily: Results of the 2018 Season

A fifth season of excavation at the late Roman rural estate of Gerace (Enna province, Sicily) took place in 2018. A rectangular kiln of the fifth century ad, partially excavated in 2017, was confirmed as having internal walls of mud brick, hardened by successive firings. It was reduced in size in a secondary period. Investigation was conducted on another of the vertical shafts, extraordinarily hacked through the thickness of parts of the mud-brick walls of this kiln in the sixth century, in order to create rudimentary furnaces, but their function remains unknown. In the bath-house of ca. 380 ad, the rest of the frigidarium, partly investigated in 2017, was uncovered. The geometric mosaic floor has an inscription on all four sides, uniquely so in the Roman Empire; it names the estate as the praedia Philippianorum. Roundels on the mosaic include monograms of ‘Asclepiades’ and ‘Capitolini’, both also named in the inscription. The text of the inscription is discussed, and possible interpretations of what it might mean are offered. Excavation found that the walls of the cold room were never finished and a horseshoe-shaped cold pool on its north side was never installed, suggesting that the baths were left incomplete, although they were used. Further evidence was found of serious earthquake damage that occurred in the second half of the fifth century. It may have happened at night if burn marks on one part of the mosaic come from dislodged torches; they and a glass lamp suggest that night bathing was practised, in line with its increasing popularity elsewhere in late antiquity. An attempt was made to repair the baths after the earthquake, but this was aborted while still in full swing, and the baths were abandoned. A small part of the early Byzantine settlement which replaced the elite buildings on the estate soon afterwards, was excavated nearby; three phases were identified, belonging to the sixth and seventh centuries. Five appendices present evidence of kiln temperature, animal bones, carbonized seeds, and wood charcoal, as revealed during the 2018 season, as well as a selection of pottery from key deposits which aids the dating of individual phases.

Carbonization temperature and charcoal properties at different positions in rectangular kiln

To increase production and decrease the heterogeneity of charcoal produced in rectangular kilns, the control of carbonization must be carried out based on the kiln internal temperature. The objective of this work was to analyze the maximum carbonization temperature and the time of thermal degradation at temperatures above 290 °C based on the internal kiln wall temperatures, in addition to evaluating charcoal properties in different positions of a rectangular kiln. Wood from the hybrid Eucalyptus urophylla x E. grandis at seven years of age was used for carbonization in rectangular kiln where temperature was monitored and controlled. Process parameters and charcoal quality were evaluated in seven positions in the rectangular kiln. Positions 1 and 7 had higher maximum temperature values and thermal degradation time at temperatures above 290 °C in comparison with the other positions, which presented similar values. There was no significant effect of kiln position on the characteristics of charcoal, which presented average values of 234.61 kg m-3 of bulk density; 55.87% of pieces with size greater than 30 mm; 19.77% of fines (granulometry < 9.5 mm); and 20.80% of friability, 75.39% of fixed carbon, 24.37% of volatile materials, and 0.24% of ash. It was concluded that the kiln position affects the temperature and time of thermal degradation; however, the control of temperature guarantees the production of homogeneous charcoal throughout the kiln, presenting satisfactory quality for steel industry usage.

Qualidade do carvão vegetal submetido a diferentes taxas de resfriamento com trocador de calor

O carvão vegetal é um importante insumo na siderurgia nacional e seu uso tem muitas vantagens sobre o carvão mineral e o coque, uma vez que é renovável, menos poluente e com baixos teores de enxofre e fósforo. A partir disso, o objetivo deste trabalho foi avaliar o desempenho do resfriamento artificial do carvão vegetal em forno retangular. Para isso, foi avaliada a influência da variação da velocidade do escoamento de gás pelo leito poroso de carvão na qualidade final do produto. Foram utilizadas quatro velocidades de escoamento, em 3 repetições, totalizando 12 ensaios de carbonizações da madeira em um forno retangular. O uso do trocador de calor proporcionou redução no tempo de resfriamento de 76 para 28 horas. A maior redução no tempo de resfriamento foi obtida com a menor velocidade de escoamento. Nas maiores velocidades ocorreu queima de uma parte do carvão na seção de saída dos gases do forno, o que provocou aumento no tempo de resfriamento. No entanto, verificou-se que essas queimas parciais não causaram diferença significativa no rendimento gravimétrico em relação à testemunha. Para as velocidades adotadas, verificou-se que não houve diferença significativa entre os tratamentos e a testemunha nos parâmetros de qualidade do carvão. Portanto, no dimensionamento de trocadores de calor, deve-se considerar a diferença de pressão entre as aberturas de sucção e injeção dos gases no forno para minimizar a infiltração de ar no forno.

Determination of connective heat transfer coefficients in an intermittent kiln

The determination of heat transfer coefficients are parameters of great importance when evaluating thermal losses in a system. Therefore, the present work reports the convective heat transfer coefficients in different positions of a rectangular kiln for the production of artisanal ceramic materials, located in Ocaña, Norte de Santander, Colombia, from which the heat losses present in the were determined. As a result, a virtual instrument was designed for temperature acquisition, using a data acquisition card, as well as a chassis and thermocouples generating a temperature report and their respective temperature profiles. The determination of heat transfer coefficients are parameters of great importance when evaluating thermal losses in a system. The energy supplied by the fuel is 51.21 kJ and the energy loss in the walls and floor of the brick kiln is 17.67 kJ, which represents 34.51% of the energy supplied. The thermal gradient in the kiln is not homogeneous, affecting the quality of the products. This will be avoided by building the walls with refractory materials.

Pyrolysis profiles of a traditional circular kiln in Austria and a drum kiln in Namibia

Charcoal production is a handicraft of oldest tradition. Various types have been developed. One of the most popular in Europe was the circular kiln with vertically piled logs. Besides traditional techniques new developments arose during the last decades like drum kilns in Namibia. Infrared spectroscopy was applied to assess pyrolysis temperatures using an already existing prediction model. A comparison of the two very different kiln techniques revealed systematic differences in the pyrolysis process and profile, but also comparable temperature ranges from 400 to 700 °C. These results correspond to literature values for circular kilns and rectangular kilns with horizontally piled logs. Temperature measurements by means of thermocouples supported infrared spectroscopic results.

Pyrolysis profile of a rectangular kiln – natural scientific investigation of a traditional charcoal production process

Rectangular kilns are a traditional technique in charcoal production in the second half of Modern Period in Middle Europe. Only in Austria there is still an active tradition that is of broader interest in an archaeological context. One of these kilns in Rohr im Gebirge, Lower Austria, was equipped with thermocouples to record pyrolysis temperature during the whole process. The removal of ready charcoal was paralleled by sampling, in total 103 charcoal samples were collected. Based on the infrared (FTIR) spectral pattern the pyrolysis temperature was predicted. It is the first reconstruction of the temperature profile of the whole kiln. Elemental analyses were performed and prediction models for carbon (R² = 0.93), hydrogen (R² = 0.96) and oxygen (R² = 0.98.) content based on FTIR spectra established. Therefore, FTIR spectroscopy rolls the degree of pyrolysis and elemental analyses into one single analytics. Further analyses by means of NMR spectroscopy, X-ray diffraction and He-pycnometry complete the picture.

UBC Excavations of the Roman Villa at Gerace, Sicily: Results of the 2017 Season

A fourth season of excavation at the late Roman rural estate of Gerace (Enna province, Sicily) took place in 2017. Two areas of kilns were investigated. In one, fragmentary evidence for six kilns was found, of which the latest was constructed of bricks bearing the monogram of the estate owner, Philippianus. In its back-fill were wasters of two roof-tile types stamped Philippiani, confirming that these were an estate production. A substantial rectangular kiln was also found 40 m to the east, with exterior stone walls but internal structures which appear to have been built of mud brick, hardened only by successive firings. This kiln too produced roof tiles (unstamped), probably in the fifth century. A smaller kiln was inserted within it in a secondary period. Later still, vertical shafts were, extraordinarily, hacked through the thickness of parts of the mud-brick walls in order to make rudimentary furnaces for an unknown purpose; this occurred in the sixth century, as shown by radiocarbon analysis of a burnt sample. In the bath-house of ca. 380 ad up the slope, the rest of the tepidarium partly investigated in 2016 was excavated, as well as a second, smaller tepidarium adjacent. The geometric mosaics of both rooms had been smashed to retrieve the bricks from the hypocausts below when the baths were decommissioned, but enough survived for the floor patterns of both to be reconstructed. Fragmentary wall veneer included coloured marbles imported from Greece, Turkey and Tunisia. Part of the frigidarium was also identified and a cold pool, one of two, was completely excavated. It had a marble floor except for one slab of sandstone, possibly a non-slip device. A fissure in the pool’s back wall suggests that an earthquake was responsible for the building’s abandonment, sometime in the second half of the fifth century. One wall of the frigidarium used pisé, highly unusual in a bath-house. The room’s floor mosaic was partly uncovered; it appears to have an inscription on all four sides, possibly uniquely so in the Roman Empire. One roundel nearer the centre of the floor was also exposed; it bears the name of Philippianus in monogram form. Study of the animal bones revealed an unusually high number of horse bones; this together with the discovery of foal bones and an equine milk tooth suggests the possible presence of a stud at Gerace.

Use of near infrared spectroscopy to distinguish carbonization processes and charcoal sources

The near infrared spectroscopy (NIRS) has shown a rapid and accurate technique for evaluation of materials of biological origin. The objective of this study was to evaluate the ability of the near infrared (NIR) spectroscopy associated to the Principal Component Analysis (PCA) for the separation of carbonization processes and identification of the origin of the woods used in the carbonizations. Hence, the charcoal of seven species of Eucalyptus and twenty native species from the Cerrado (savannah) of Minas Gerais, Brazil were investigated. The Eucalyptus wood was carbonized in a laboratory furnace and in a 190 m³ industrial rectangular kilns while the wood of native vegetation was carbonized only under laboratory conditions. The samples were grinded for NIR spectra acquirement. The NIR spectra were analyzed by PCA but no cluster were identified allowing discrimination between charcoal produced from native and from Eucalyptus wood. However, the cluster formed in the PCA when using the first derivative NIR spectra permitted to distinguish charcoal produced in different processes of carbonization. Two groups of data for charcoal produced in the industrial rectangular kilns were also observed, suggesting heterogeneity in the carbonization process.

Avaliação econômica e financeira de projetos de fornos dos tipos container industrial e retangular de 40 estéreos

Este trabalho teve como objetivo principal a análise econômica e financeira de um projeto com 100 fornos tipo container industrial e 100 fornos tipo retangular de 40st. para a produção de carvão vegetal. Para tanto, utilizaram-se como indicadores financeiros a lucratividade, rentabilidade, prazo de retorno do investimento e ponto de equilíbrio. Os indicadores econômicos utilizados para proceder a análise econômica foram o VPL, TIR, B(C)PE e B/C. Concluíram que os fornos são viáveis do ponto de vista econômico e financeiro. Entretanto o forno container por ter maior VPL daria um retorno mais lucrativo quando comparado ao retangular de 40 st.

The production of tin-glazed ware on the north bank of the Thames: excavations at the site of the Hermitage Pothouse, Wapping

Archaeological fieldwork was undertaken during 1996 at the Hermitage Basin site, Wapping, in the London Borough of Tower Hamlets. The work, funded by the London Docklands Development Corporation, was in advance of the redevelopment of the site. The area of excavation was defined by the positions of the proposed buildings and known features which truncated the archaeological deposit.Documentary evidence indicated that the Hermitage Pothouse was situated at the head of the former Hermitage Dock. This tin-glaze (delft) manufactory was in production from c. 1665 to c. 1773. During this period it was the only tin-glaze pothouse in London north of the Thames. Before the present excavation it was not possible to attribute any vessels to this pothouse.After 1781 the pothouse was converted to become Jones Foundry. After this the Hermitage Dock was extended north onto the foundry site. The Hermitage Dock was then sold in 1801 and backfilled in preparation for the construction of the London Dock. The Hermitage Basin linking the London Dock to the Thames was completed by the beginning of 1805.The excavation revealed two successive bottle kilns, of a type normally associated with the manufacture of stoneware or earthenware. No evidence for the manufacture of anything other than tin-glazed ware was recovered. Post-dating these kilns was a rectangular kiln, the firebox of which survived. This was in use after 1720. There was evidence that this kiln manufactured tin-glazed wall tiles and possibly stoneware. In addition to tile, finds included a range of kiln furniture (with forms distinctive to this site), many different forms of biscuit ware (with evidence for the manufacture of 17th-century forms continuing into the 18th century), and glazed ware. The range of forms recovered indicates that Wapping needs to be included with Southwark and Lambeth as a centre of manufacture in the period 1665–1773.

NEW METHOD OF DIRECT FIRING GLAZED CERAMIC BODIES1

ABSTRACTA description is given of the construction, operation, and economies of an adaptation of Carboradiant principle of heating to a rectangular kiln used for firing sanitary ware. Improvement in control, increase in fist quality ware, and economy of fuel resulted.