Method and sieve system for screening material

A method for screening material in a sieve system comprising:

• a sieve for screening material by selectively passing first particles of the material and not passing second particles of the material based on respective dimensions of the first and second particles relative to dimensions of screening apertures in the sieve;
• a holding container for feeding material to be screened to the sieve;
• and
• a fines container for receiving the first particles screened by the sieve, the method comprising:
• measuring a first fines container load at a first time;
• measuring a second fines container load at a second time;
• determining a fines rate by determining a rate of change of the fines container load based on the measured first and second fines container loads and the first and second times;
• determining an operating condition of the sieve system based on the determined fines rate;
• determining that the fines rate is equal to or lower than a fines rate low set point and determining the operating condition to be representative, or further representative, of an excess of material on the sieve;
• and
• discharging material from the sieve to an oversize discharge outlet for removing the second particles from the sieve in response to determining the operating condition to be representative, or further representative, of an excess of material on the sieve.

A sieve system for screening material, the sieve system comprising:

• a sieve for screening material by selectively passing first particles of the material and not passing second particles of the material based on respective dimensions of the first and second particles relative to dimensions of screening apertures in the sieve;
• a holding container for feeding material to be screened to the sieve;
• a fines container for receiving the first particles screened by the sieve;
• a fines load sensor for measuring a fines container load;
• a controller configured to:
• measure a first fines container load at a first time;
• measure a second fines container load at a second time;
• determine a fines rate by determining a rate of change of the fines container load based on the measured first and second fines container loads and the first and second times;
• determine an operating condition of the sieve system based on the determined fines rate;
• and
• determine the operating condition to be representative of a damaged or missing sieve responsive to determining that the fines rate is equal to or greater than a fines rate high set point;
• an oversize container for receiving the second particles screened by the sieve;
• an oversize load sensor for measuring an oversize container load;
• and
• an oversize discharge outlet for removing the second particles from the sieve into the oversize container,
• wherein the controller is further configured to:
• measure a first oversize container load at a third time;
• measure a second oversize container load at a fourth time, wherein a period between the third and fourth times does not include operation of the sieve system to discharge material to the oversize discharge outlet for removing the second particles from the sieve;
• determine an increase in the oversize container load based on the measured first and second oversize container loads;
• and
• determine a fault condition with the oversize discharge outlet in response to determining the increase in the oversize container load.