Mineral processing

Crushing and milling. Crushing extracted naba is initially by hand using a sledge hammer and a sizeable rubber ring usually about two inches high and eight inches in diameter. The raw naba is placed onto this ring and is hammered to bits. The ring keeps the ore in place and not scattering its valuable contents in the hammering process. A modification of this process is by using a fabricated hammer mill (replicated from the jaw crusher that is used in large scale milling).

Grinding. Traditional fine grinding methods use the gaid, manually grinding the crushed ore between two heavy abrasive stones that are shaped (by continuous use) into a boat-like mortar and a ball-like pestle. The modification is a miniaturized replica of the conventional rod or ball mill.

Gold Recovery. After milling naba into a sticky dough-like texture, ore is washed from the mill and sluiced. Sluice boxes are fitted with either a woolen blanket or a jute sack. The fine concentrated (naba) ore sometimes referred to as linangis further soaked or leached in a pond that is either mixed with natural solutes that enhances the wetting qualities of water and enhancing the separation of metals from the non-metallic elements in the ore. This process of leaching also uses herbal preparations like sunflower leaves or calamansi into the muck.

Modern leaching uses either potassium cyanide or calcium cyanide as wetting agent. The leaching process can take a month to let most of the metallic particles separate from the clay. Traditional small-scale gold producers separate the gold from the ore by means of dayasor yakayak, this is by carefully winnowing the rock dust from the heavier metallic particles. A more cheaper and dangerous method is soaking the final product onto mercury -all metallic particles win into the mercury and the non-metallic particles remain with the wash water. The use of mercury is not encouraged or even totally banned in traditional mining.

Another process of gold recovery can be done on mine tailings as a method of re-processing what is supposed to be thrown away. This process commonly referred to as lugaba is by recovering as much tailings and leaching these into a chemical mixture for a given time to further crack the remaining soluble materiel and concentrate the metallic contents.

Lugaba requires extensive experience in evaluating the minute characteristics of the mine tailings in order to maximize the profitability of recovering gold.

Gold Purification – Panagpuro. The traditional process is by using the common tools in blacksmithing—a furnace (pugon) a crusicble (gangi), borax and a lot of patience.

In the process of gold recovery, it is important to know that work designations do not discriminate gender. Roles of women in the gold recovery process, usually beginning from the panaggiling stage is equally important as the miner and mucker in the usok.

Women are more involved (but not limited to) in the ore cracking process up to the purification process where most known and skilled handlers of the gangi are women. Men nevertheless are not limited to the initial stages of gold ore extraction work as they can also do purification work.

Cleaning up in the pogon work area is a tedious and meticulous process, carefully cleaning the surrounding area of the furnace, gathering all the ash and left-over charcoal, crushing all the used crucibles and reprocessing these wastes for residual gold. This process is often designated to the apprentices who would happily do it to upgrade their skills and earn the reward of owning the recovered gold in the process.

When the gold is assayed and readied for the market, usually all the participants in the process are enjoined to keep together in vigilant watch until the gold is sold.

Proceeds from the sale is initially kept while the process of accounting of expenditures is taken up. Expenses of the supply is totally reimbursed and appropriately complimented by a previously agreed (purcinto). What is left is equally shared. Win or loss, the gang is kept conscious of the whole process of turning rock into gold.