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Block Models

The block model commands: build a block model from a file, from scattered samples or over your drawing; estimate it from drillholes; colour, cut, edit and check it; report tonnes and grade; and find an optimal open pit. Each command has its own section; press F1 over a ribbon button, or the ? in the title bar of a command's window, to open it.

Most commands work on the selected block model; if none is selected they use the first block model in the project. When the project has no block model they say "No block model in the project."

Import

Reads a block model from a flat CSV or TSV file with one row per cell, and builds it as a new block model on the layer "Block model".

Where to find it

Geology tab → Block model group → Import. With a block model selected the same button is on the Block model tab.

Before you start

• A text file (.csv, .tsv or .txt) with one row per cell.
• The file needs the cell centre in three columns. These names are accepted whatever the letter case and whatever separates the words: X: XC, X, CentroidX, Easting, East, MidX; Y: YC, Y, Northing, North, MidY; Z: ZC, Z, Elevation, Elev, RL, MidZ.
• Every other column that holds a number in at least one row becomes a numeric column of the model. Text columns are ignored.
• A rock column is recognised by one of these names: rock, rocktype, rockcode, domain, zone, lith, lithology, material, mat. A column named blockfactor, factor, pctinside or percent is read as the block factor of the cell.
• A file where each row has its own size (columns such as XINC, YINC, ZINC, DX, DY, DZ, or an underscored copy of the centre column such as _EAST) is read as a sub-blocked model: the cells are kept as they are in the file.

How to

1. Click Import.
2. Choose the file in the Import block model dialog.
3. The file is read in the background. When it is done a message lists what was built.

The model is added in one undoable step and coloured at once, by a grade column when there is one, otherwise by rock.

The message shows the grid ("Grid: nx × ny × nz (n cells)") and the cell size, or for a sub-blocked file "Sub-blocked model: n cells kept as in the file, each its own size"; then the columns, "Rock assigned from the file." when a rock column was found, and "n row(s) skipped." for rows without a usable centre.

If something goes wrong

What next

Colour cells · Validate · Tonnage

Import samples

Builds a block model from scattered samples (an assay file whose positions do not lie on a grid). You choose one cell size; each sample goes into the cell it falls in.

Where to find it

Geology tab → Block model group → Import samples.

Before you start

A CSV, TSV or TXT file with one row per sample and X, Y and Z columns named as in Import. Rock, block factor and numeric columns are recognised in the same way.

How to

1. Click Import samples and choose the file.
2. In the Cell size window the first section (Samples) shows how many samples the file has and their X, Y and Z ranges. The second section holds the Cell size box with − and + buttons. One size is used for X, Y and Z. The window suggests a size of about one thirtieth of the largest range.
3. The grid you would get ("Grid: nx × ny × nz (n cells)") is shown under the box. A smaller size gives more cells.
4. Click Import. A message lists the grid, the cell size ("Cell size"), "Samples used: n", the columns and skipped rows.

A sub-blocked file (each row its own size) is read as it is, without asking for a cell size.

How samples are combined

• A numeric column is the average of the samples in the cell. A column whose name contains tonnage, tonnes, tonne, mass, weight, volume or count is summed instead.
• The rock of a cell is the rock with the most samples in it.
• A cell no sample reaches stays empty.

If something goes wrong

What next

Estimate from drillholes · Colour cells

Create

Creates an empty block model of cubic blocks over the selected objects, or over the whole drawing when nothing is selected.

Where to find it

Geology tab → Block model group → Create.

How to

1. Optionally select the objects the model must cover.
2. Click Create.
3. In the Create block model window set Block size and confirm.
4. A message reports "Created a block model with n cells."

Parameters

The model goes on the layer "Block model" (made if it does not exist), as one undoable step. It has no columns yet: add them with Columns, fill them with Calculator or Assign.

If something goes wrong

Colour cells

Chooses how the cells of the block model are painted: by a numeric column along a colour scale, or each cell in the colour of its rock.

Where to find it

Geology tab → Block model group → Colour cells. On the Block model tab it is in the View group.

How to

1. Click Colour cells. If no block model has a numeric column or a rock, you get "No block model with a numeric column to colour by."
2. In the Colour cells window choose a column in Colour cells by, or By rock.
3. Adjust the scale and the visible range. The 3D view follows at once.
4. Click Close. Turn off shows the models as boxes again.

Parameters

With By rock the colours are the rocks' own; change them in the rock table. The window states how many cells are shown ("n cell(s) shown."). The colouring is not saved with the project; a model that is opened or imported gets its default colouring again.

What next

Raise cutoff · Section plane

Raise cutoff

Hides low-grade cells. Each click raises the lower limit of the visible range to the next step of the colour scale: 25 %, 50 %, 75 %, 90 % of the scale, and then back to showing every cell.

Where to find it

Geology tab → Block model group → Raise cutoff. On the Block model tab it is in the View group.

How to

1. Colour the cells with Colour cells; otherwise you get "Colour the cells first, then raise the cutoff."
2. Click Raise cutoff. A message says "Hiding cells below x." or "Showing every cell."

Tonnage

Shows the tonnage of the block model above a cutoff grade of 0.5, using the model's column named grade.

Where to find it

Geology tab → Block model group → Tonnage drop-down → Tonnage. On the Block model tab: Calculation group.

How to

Click Tonnage. A message lists, above the 0.5 cutoff: Cells, Volume in m³, Tonnes, Average grade, Contained metal.

A cell is weighed by the density of its rock where the rock has one in the rock table.

If something goes wrong

Tonnage by domain

The same as Tonnage (cutoff 0.5, column grade), split by rock. Each row gives the domain, tonnes, grade and metal, the largest tonnage first.

Where to find it

Geology tab → Block model group → Tonnage drop-down → Tonnage by domain. On the Block model tab: Calculation group.

If something goes wrong

Grade-tonnage curve

Shows tonnes, grade and metal of the grade column at ten evenly spaced cutoffs.

Where to find it

Geology tab → Block model group → Tonnage drop-down → Grade-tonnage curve. On the Block model tab: Calculation group.

How to

Click Grade-tonnage curve. A message lists one row per cutoff: cutoff, tonnes, grade, metal. If the column has no values you get "The block model's grade column has no values."

Tonnage by bench

Shows tonnes, grade and metal above the cutoff 0.5 (column grade), one row per bench, a bench being a layer of cells in Z.

Where to find it

Geology tab → Block model group → Tonnage drop-down → Tonnage by bench. On the Block model tab: Calculation group.

How to

Click Tonnage by bench. The message "Above 0.5 cutoff — bench, tonnes, grade, metal:" lists the rows.

Validate

Checks the block model for inconsistencies before you trust a report on it.

Where to find it

Geology tab → Block model group → Validate. On the Block model tab: Edit group.

How to

Click Validate. The message is "No problems found." or a list of these findings:

• n cell(s) point at a rock that no longer exists.
• n cell(s) have a block factor outside 0–1.
• Column 'name' has no values at all.

Reblock

Combines every group of cells into one larger cell, averaging their values.

Where to find it

Geology tab → Block model group → Reblock. On the Block model tab: Edit group.

How to

1. Click Reblock.
2. In the Reblock window set how many cells become one along each axis and confirm.
3. A message says "Reblocked to n cells." The old model is replaced by the new one in one undoable step.

Parameters

If something goes wrong

Export

Writes the block model as a flat CSV file, one row per cell.

Where to find it

Geology tab → Block model group → Export. On the Block model tab: Exchange group.

How to

1. Click Export and choose the file in the Export block model dialog.
2. A message says "Exported n cells."

The file has the columns XC, YC, ZC, then (for a sub-blocked model) XINC, YINC, ZINC, then every numeric column, ROCK (the rock's name) when the model has rocks, and BLOCKFACTOR when it has a block factor. Import reads this shape back.

If the file cannot be written you get "Could not write the block model file '…': …".

Section plane

Cuts the block model with planes you move and turn about the model's three axes, to look inside it.

Where to find it

Geology tab → Block model group → Section plane. On the Block model tab: View group.

The Section planes window does not block the program; running the command again brings it forward. If the cells have no colouring yet, they are coloured first so the cut shows.

How to

1. Click Section plane.
2. Add a plane with Horizontal (through the middle of the model), Along X or Along Y (vertical planes along the model axes).
3. Choose the plane in the Planes list. The tick box next to it sets whether this plane cuts the model.
4. Set its position and rotation in the boxes, or drag it with the gizmo in the 3D view. While you drag, a slice or the sections alone show as the model's frame, and are drawn again when you let go.
5. Flip side cuts away the other side of the plane (the gizmo Z arrow points to the side cut away). Remove deletes the chosen plane.
6. Choose the Section view and click Close. The planes are stored with the block model in one undoable step: "The planes stay with the block model; Undo takes back the whole change."

Parameters

The same display can be chosen in Properties while the window is open; the two stay in step.

Cell info

A tool: click a cell of a block model in the 3D view to see everything it holds and to change it.

Where to find it

Geology tab → Block model group → Cell info. On the Block model tab: View group.

How to

1. Click Cell info. The tool starts.
2. Click a cell that shows in the 3D view. The cell is outlined, and the Block model cell window opens. Its header gives the cell as "Cell i, j, k" and the centre coordinates.
3. The window shows Rock type (a choice from the rock table) and Values: one box per column. Type a value and press Enter or leave the box: "name changed." appears; an empty box means no value. A text that is not a number gives "'x' is not a number."
4. Click another cell to look at it.
5. Press Esc, or click the button again, to end the tool. The window closes.

Each change is one undoable step. A model on a locked layer cannot be changed: "The block model is on a locked layer."

Columns

Adds, renames and removes the columns of a block model.

Where to find it

Geology tab → Block model group → Columns. On the Block model tab: Edit group.

How to

1. Click Columns. The Block model columns window lists the columns ("The model has no columns yet" when empty).
2. To add: type a Name and a Value (what every cell of the new column holds; empty means no value) and click Add.
3. To rename: choose a column, type the new Name and click Rename column.
4. To remove: choose a column and click Remove, then confirm "Take the column 'x' away, values and all? Undo brings it back."

The window confirms with "Column 'x' added.", "Column 'x' is now 'y'." or "Column 'x' removed."

If something goes wrong

Calculator

Works out a column from a formula, for all cells or only those that meet a condition.

Where to find it

Geology tab → Block model group → Calculator. On the Block model tab: Edit group.

How to

1. Click Calculator. The window lists the model's columns.
2. In Column to write choose a column or type the name of a new one.
3. Type the Formula, for example grade * 2. The window checks it as you type: it shows how many cells it would give and the first values, or the fault with its position.
4. Optionally type a Condition, for example rock = "Magnetite" and grade > 0.5. Empty means every cell.
5. Choose Cells: All cells, or Only the cells shown (the cells the colouring draws, and only the slice when the section planes show one).
6. Click Calculate. The window says "n cell(s) of 'x' calculated." One undoable step; cells that fail the condition keep their values.

The formula language

Columns are used by name (write [name] when it has spaces), plus rock, numbers, + - * / ^, if(c, a, b), min, max, abs, sqrt, ln, log, exp, round, floor, ceil. Text is compared with text only by = or <>.

If something goes wrong

Assign

Gives the cells of a region a value in a column, or a rock.

Where to find it

Geology tab → Block model group → Assign. On the Block model tab: Edit group.

How to

1. Click Assign.
2. Under Region choose Inside an object and pick a Surface or closed line (a closed surface, i.e. a wireframe, or a closed line in plan), or choose The cells shown. The window counts the cells: "n cell(s) in the region."
3. For a line in plan you may limit the elevation with Elevation from / to (in metres; empty means no limit).
4. Under What to assign choose A value (a column of the model or the name of a new one, and the value; empty means no value) or A rock (from the rock table).
5. Click Assign. The window says "n cell(s) assigned." One undoable step.

If something goes wrong

Table

Shows the cells of a block model as a table that you can sort and edit.

Where to find it

Geology tab → Block model group → Table. On the Block model tab: Edit group.

How to

1. Click Table.
2. Columns are i, j, k (cell indexes), X, Y, Z (the centre), dX, dY, dZ for a sub-blocked model, Rock type and one column per model column. The index and centre columns are read-only.
3. Click a header to sort. Edit a value in a cell, or choose a rock in the Rock type column. A value that is not a number gives "'x' is not a number." and "There is no rock 'x' in the rock table." for an unknown rock.
4. Options: Only the cells shown (the cells the colouring draws, and only the slice when the section planes show one) and Only cells with a value (leaves out cells with no value in any column and no rock).

The window shows "n of n cells" and "No cells to show" when nothing matches. Each change is one undoable step.

Rocks by bodies

Gives each cell whose centre lies inside a geological body the rock of that body. Where bodies overlap, the winning body decides. Cells outside every body keep their rock.

Where to find it

Geology tab → Block model group → Rocks by bodies. On the Block model tab: Edit group.

Before you start

Geological bodies with closed wireframes and rocks.

How to

Click Rocks by bodies. The model is coloured by rock and a message says "n of n cells are inside geological bodies, n changed rock. Cells outside the bodies keep their rock." Bodies that could not be used are listed. One undoable step.

If something goes wrong

Estimate from drillholes

Estimates a column of the block model from the composites or samples of the drillholes, by inverse distance, nearest sample or ordinary kriging, in a search ellipsoid.

Where to find it

Geology tab → Block model group → Estimate from drillholes. On the Block model tab: Edit group.

Before you start

A block model and drillholes with samples or composites. Otherwise the button is off with "Needs a block model and drillholes with samples."

How to

1. Click Estimate from drillholes.
2. Fill in the Estimate from drillholes window (tables below). A warning line says what is wrong and Estimate stays off; otherwise the line shows "n sample(s) of x from n hole(s); n cell(s) to estimate."
3. Click Estimate. The work runs in the background with a progress window ("Estimating the cells") that you can cancel.
4. A message gives the result, for example "n of n cell(s) estimated into x from n sample(s)", the mean and range, and how many samples were taken at the top cut.

The estimate is written into the target column in one undoable step, and the model is coloured by it. The settings are kept with the project; choosing a column estimated before starts from how it was estimated.

1 Values

2 Method

3 Search

If the radii are not positive, the power is outside 0 to 5, or the most samples are fewer than the least, the window says "The radii must be positive, the power 0 to 5, at least one sample, the most not below the least."

Variogram window

Opened with Variogram…. It works out the experimental variogram of the chosen samples and fits a model.

Fit to the points fits the model to the experimental points. The nugget and the sill must not be below zero, together above it, and the ranges positive. Use this model returns to the estimate window, which takes the model's ranges and azimuth as the search.

If something goes wrong

What next

Classify resources · Swath plot · Model against samples

Classify resources

Puts each estimated cell into a resource class by how near and how many its samples are. Each cell goes into the surest class whose rule it meets.

Where to find it

Geology tab → Block model group → Classify resources. On the Block model tab: Edit group.

Before you start

A column estimated with Estimate from drillholes with the option to write the number of samples and the nearest distance. Otherwise the button is off: "Estimate a column from the drillholes first, with its number of samples and distance."

How to

1. Click Classify resources.
2. Choose the Estimated column, the Names of the classes and the Into the column that receives the class codes.
3. Set the rules, the surest class first.
4. Click Classify. The class codes are written in one undoable step and the model is coloured by them.

Parameters

The window counts the cells of each class. It refuses odd rules: "Each class needs a distance above 0 and at least one sample." and "A surer class may not reach farther or take fewer samples than the next."

What next

Resource report

Resource report

A table of tonnes, mean grade and metal by resource class above each cutoff, which you can export to CSV.

Where to find it

Geology tab → Block model group → Resource report. On the Block model tab: Calculation group.

How to

1. Click Resource report. The window does not block the program.
2. Choose the columns and set the options; the table updates as you change them.
3. Click Export report… to write the table as CSV; Close ends.

The table has the columns Class, Cutoff, Cells, Volume m³, Tonnes, Mean grade, Metal.

Parameters

If the model has no column to report you get "The block model has no column to report."

Swath plot

Compares the block model with the drillhole samples band by band along an axis, with the samples declustered by cells. It shows whether the model is biased.

Where to find it

Geology tab → Block model group → Swath plot.

Before you start

A block model and drillholes with samples; otherwise the button is off with "Needs a block model and drillholes with samples."

How to

1. Click Swath plot. The window does not block the program.
2. Choose the Column, the Drillholes source (Composites or Samples) and the axis in Bands along.
3. Set Band, m and Declustering cell, m, or click Find cell, which tries cell sizes from one block to twenty and takes the one that gives the lowest declustered mean.
4. Read the chart: three lines, Model, Samples and Declustered. The summary gives "Means: model …, samples … (n), declustered …; the model … the declustered samples."
5. Export rows… writes the bands as CSV: From, To, Model mean, Cells, Sample mean, Declustered mean, Samples.

Parameters

Band and cell must be above 0: "⚠ Type a band and a cell above 0."

Blast blocks against the model

Grades the blast blocks from the block model: tonnes, ore and waste at a cutoff, dilution and ore lost.

Where to find it

Geology tab → Block model group → Blast blocks against the model. The same button is on the Blast Design tab, Calculation group.

Before you start

A block model and blast blocks (otherwise the button is off: "Needs a block model and blast blocks."). With blast blocks selected only those are graded, otherwise all.

How to

1. Click Blast blocks against the model. The window does not block the program.
2. Choose the Grade column and type the Cut-off (default 0.5, the lowest grade of ore) and Density otherwise, t/m³ (default 2.7).
3. Read the table, one row per block: Block, Top, Floor, Tonnes, Mean grade, Ore t, Ore grade, Waste t, Goes as (Ore or Waste), Dilution %, Ore lost t.
4. The summary line gives the totals: "n block(s), n t; sent as ore n t, of it waste n t (…); ore lost with the waste n t."
5. Export rows… writes the table as CSV.

The cutoff and the density must be numbers and the density above 0: "⚠ Type a cut-off and a density above 0."

Model against samples

Reconciles the block model with drillhole samples: bias, correlation and slope, over all samples and by bench.

Where to find it

Geology tab → Block model group → Model against samples.

Before you start

A block model and drillholes with samples; otherwise "Needs a block model and drillholes with samples."

How to

1. Click Model against samples. The window does not block the program.
2. Choose the Drillholes (all, or the selected ones), the source in From (Composites or Samples), the Column and the Bench, m (the height of a bench the figures are split by; starts at the cell's Z size).
3. The table has one row for All and one per bench: Bench, Samples, Sample mean, Model mean, Bias %, Correlation, Slope. A scatter chart plots Model against Samples.
4. The summary reads "n sample(s) in cells of the model: the model reads … against the samples; correlation …, slope … (1 when its high cells are as rich as it says)."
5. Export rows… writes the table as CSV.

If no sample falls in a cell with a value you get "No sample of x lies in a cell of the model with a value."

Optimise pit

Finds the most valuable open pit of the block model at a given slope angle, and the nested pits at lower and higher prices. A block goes to the plant when its metal pays for processing; a pit is the set of blocks of greatest value whose slopes stand.

Where to find it

Geology tab → Open pit group → Optimise pit.

Before you start

A regular block model; a sub-blocked model must be reblocked first ("The pit is optimised on a regular grid: reblock the sub-blocked model first."). The model needs a grade column.

How to

1. Click Optimise pit.
2. Fill in the window and click Optimise. The work runs in the background ("Finding the pits") and can be cancelled.
3. Each cell's least revenue factor is written into the column pit_rf in one undoable step, and the model is coloured by it.
4. The Nested pits window opens. Choose a pit and click Add pit surface to add the bottom of that pit to the project as a surface on the active layer, or Export rows… for CSV.

Parameters

The values are kept between runs. The Nested pits table has the columns Revenue factor, Blocks, Ore t, Waste t, Strip ratio, Mean grade, Metal, Pit value. The value is undiscounted, at the full price.

If something goes wrong

What next

Pit outlines

Pit outlines

Draws the outlines of an optimised pit level by level: a closed line at the floor of each level round the pit's cells, on the active layer. The lowest level is the floor a pit design starts from.

Where to find it

Geology tab → Open pit group → Pit outlines.

Before you start

Run Optimise pit first; otherwise the button is off with "Optimise the pit first."

How to

1. Click Pit outlines.
2. In the window choose the Revenue factor of the pit (it starts at 1 or the nearest above) and click Draw.
3. The outlines are added as polylines in one undoable step. A message says "n outline(s) drawn."

If the pit takes no block you get "The optimised pit takes no block."