// workload interface

public interface Workload {

    void compute();
}

// workload runnable

public class WorkloadRunnable implements Runnable {
    private static final double MAX_MILIS_PER_TICK = 2.5;
    private static final int MAX_NANOS_PER_TICK = (int) (MAX_MILIS_PER_TICK * 1E6);

    private final Deque<Workload> workloadDeque = new ArrayDeque<>();

    public void addWorkLoad(Workload workload) {
        this.workloadDeque.add(workload);
    }

    @Override
    public void run() {
        long stopTime = System.nanoTime() + MAX_NANOS_PER_TICK;

        Workload nextLoad;

        while (System.nanoTime() <= stopTime && (nextLoad = this.workloadDeque.poll()) != null) {
            nextLoad.compute();
        }
    }
}

// Placeable block

@AllArgsConstructor
public class PlaceableBlock implements Workload {
    private final UUID worldID;
    private final int blockX;
    private final int blockY;
    private final int blockZ;
    private final Material material;

    @Override
    public void compute() {
        World world = Bukkit.getWorld(worldID);
        world.getBlockAt(blockX, blockY, blockZ).setType(material);
    }
}

// my code

            FileUtil util = new FileUtil(FileUtil.getDataFile("test.yml", "mines"));
            YamlConfiguration configuration = util.getConfiguration();
            Location center = new Location(player.getWorld(), 600, 50, 600);

            for (String key : configuration.getKeys(false)) {
                if (!key.equalsIgnoreCase("data")) {
                    ConfigurationSection section = configuration.getConfigurationSection(key);
                    double x = section.getDouble("x") + center.getX();
                    double y = section.getDouble("y") + center.getY();
                    double z = section.getDouble("z") + center.getZ();

                    runnable.addWorkLoad(new PlaceableBlock(player.getWorld().getUID(), (int) (x), (int) (y), (int) (z), Material.valueOf(section.getString("material"))));
                }
            }