PEAT BURNING    SALT PRODUCTION

As the sea level receded, the huge flat coastal areas again appeared and allowed access to the marshes, the meers, claires, and broads, and peat became available as a fuel for burning, Leaching the salt from the peat ashes became a competitive method of winning salt, instead of wood, and the inland salt springs

 

Salt Production - Boiling with PEAT fuel

Peat was recycled: first it was dug in coastal areas, after being soaked at high tide, and then dried and burned. Salt was further dissolved from the peat ash by seawater, as it was filtered through.

x-section of peat prod


The coastline cross section with turfs of peat soaking in sea brine. Note the receding coast , which was later to form the "meres"


The brine concentrate was evaporated in cauldrons, with the peat again being used to fuel the fire. In order to eliminate unwanted contamination, eggshells were thrown into the cauldren, to which the unwanted particles adhered, and the skum was skimmed off the surface of the boiling brine. In another description of year 1556, a chemical process used today, was employed, Flotationpeat


Characteristic scheme of peat salt making as reconstructed for the German North Sea coast from remnants of islands showing the changing shorelines


 


Medieval salt production in Zeeland and surroundings dr. K.A.H.W. Leenders  : paintingby  Darink Delven at the Zierikzee townhall-museum, showing the first phases of the saltproduction process   "Darinck Delven
Ashes of saltproduction from peat and seawater. Analysis of "Zel as" at Steenbergen, province North-Brabant, The Netherlands K.A.H.W. Leenders

The whites of eggs were used to create additional froth, to bring the impurities to the surface for skimming, and by bringing the slurry to a quick boil. Other additions used were pouring a small quantity of animal blood in the cauldren, or pouring some of "the best and strongest ale" The final concentrate of some 50% to 90% , a wet salt sludge which could be molded was then dried out in small clay molds set between the large pots. The salt cakes formed were more or less constant in size and weight to about 200 grms, though it varied. In Mexico using the 'Sal Cochidas' molds of thick ceramic cylinder shape were even smaller


How much peat is needed for 1 cubic meter salt?
dr. K.A.H.W. Leenders




The peat turfs cut and arranged in rows for soaking in the sea brine

The process for salt boiling consisted of dumbbell shaped supports for the big pots and cup-like moulds resting between them. The pots were continually refilled with 'make-up' new brine, The wet moulds with growing crystals prevented the inner side of the vessels from getting any hotter than 100C degrees, even though the outside of the vessels was exposed to the flames of the fire. This crude firing of the clay moulds for this specific purpose, may be the origin of pottery. The enormous amount of half burned sherds, found in the 'red hills' on marshy coasts, bear witness to the undeniable enormity of activity in salt making, where and when the sealevel was suitable.


boil1boil2

Technique for boiling brine over a fire - Agricola De re metallica, Basle [1556] and ceramic molds


[see research of (Lost Peatlands. Research of the situation and exploitation of now disappeared peatlands in the area between Antwerpen, Turnhout, Geertruidenberg and Willemstad. 1250-1750)

Agricola De re metallica, Basle [1556]  THE IDEAL SYSTEM INCORPORATING SOLAR EVAPORATION AND

 CONTROLLED BATCH HARVESTING FROM SLURRY TO DRY SALT SOLIDS  THROUGH A SERIES OF PANS


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